Volt - unit of electrical potential or motive force - potential is required to send one ampere of current through one ohm of resistance
Ohm - unit of resistance - one ohm is the resistance offered to the passage of one ampere when impelled by one volt
Ampere - units of current - one ampere is the current which one volt can send through a resistance of one ohm
Watt - unit of electrical energy or power - one watt is the product of one ampere and one volt - one ampere of current flowing under the force of one volt gives one watt of energy
Volt-ampere (VA) - is a measurement of power in a direct current ( DC ) electrical circuit. The VA specification is also used in alternating current ( AC ) circuits, but it is less precise in this application, because it represents apparent power , which often differs from true power .
Kilovolt Ampere - one kilovolt ampere - KVA - is equal to 1000 volt amperes
Power Factor - ratio of watts to volt amperes
Most important Formulas:
Voltage V = I × R = P / I = √(P × R) in volts V
Current I = V / R = P / V = √(P / R) in amperes A
Resistance R = V / I = P / I2 = V2 / P in ohms Ω
Power P = V × I = R × I2 = V2 / R in watts W

Electrical Potential - Ohm's Law
Ohm's law can be expressed as:
V = R I (1a)
V = P / I (1b)
V = (P R)1/2 (1c)
Electric Current - Ohm's Law
I = V / R (2a)
I = P / V (2b)
I = (P / R)1/2 (2c)
Electric Resistance - Ohm's Law
R = V / I (3a)
R = V2/ P (3b)
R = P / I2 (3c)
Electric Power
P = V I (4a)
P = R I2 (4b)
P = V2/ R (4c)
where
P = power (watts, W), V = voltage (volts, V)
I = current (amperes, A), R = resistance (ohms, Ω)
Electric Energy :Electric energy is power multiplied time, or
W = P t (5)
where
W = energy (Ws, J), t = time (s)
Electrical Motors : Electrical Motor Efficiency
μ = 746 Php / Pinput_w (6)
where
μ = efficiency
Php = output horsepower (hp)
Pinput_w = input electrical power (watts)
or alternatively
μ = 746 Php / (1.732 V I PF) (6b)
Electrical Motor - Power
P3-phase = (V I PF 1.732) / 1,000 (7)
where
P3-phase = electrical power 3-phase motor (kW)
PF = power factor electrical motor
Electrical Motor - Amps
I3-phase = (746 Php) / (1.732 V μ PF) (7)
where
I3-phase = electrical current 3-phase motor (amps)
PF = power factor electrical motor
Electrical measurements
Quantity
Name
Definition
frequency f
hertz (Hz)
1/s
force F
newton (N)
kg•m/s²
pressure p
pascal (Pa) = N/m²
kg/m•s²
energy E
work joule (J) = N•m
kg•m²/s²
power P
watt (W) = J/s
kg•m²/s³
electric charge Q
coulomb (C) = A•s
A•s
voltage V
volt (V)= W/A
kg•m²/A•s³
current I
ampere (A) = Q/s
A
capacitance C
farad (F) = C/V = A•s/V = s/Ω
A²•s4/kg•m²
Volt - unit of electrical potential or motive force - potential is required to send one ampere of current through one ohm of resistance
Ohm - unit of resistance - one ohm is the resistance offered to the passage of one ampere when impelled by one volt
Ampere - units of current - one ampere is the current which one volt can send through a resistance of one ohm
Watt - unit of electrical energy or power - one watt is the product of one ampere and one volt - one ampere of current flowing under the force of one volt gives one watt of energy
Volt-ampere (VA) - is a measurement of power in a direct current ( DC ) electrical circuit. The VA specification is also used in alternating current ( AC ) circuits, but it is less precise in this application, because it represents apparent power , which often differs from true power .
Kilovolt Ampere - one kilovolt ampere - KVA - is equal to 1000 volt amperes
Power Factor - ratio of watts to volt amperes
Most important Formulas:
Voltage V = I × R = P / I = √(P × R) in volts V
Current I = V / R = P / V = √(P / R)
Ohm - unit of resistance - one ohm is the resistance offered to the passage of one ampere when impelled by one volt
Ampere - units of current - one ampere is the current which one volt can send through a resistance of one ohm
Watt - unit of electrical energy or power - one watt is the product of one ampere and one volt - one ampere of current flowing under the force of one volt gives one watt of energy
Volt-ampere (VA) - is a measurement of power in a direct current ( DC ) electrical circuit. The VA specification is also used in alternating current ( AC ) circuits, but it is less precise in this application, because it represents apparent power , which often differs from true power .
Kilovolt Ampere - one kilovolt ampere - KVA - is equal to 1000 volt amperes
Power Factor - ratio of watts to volt amperes
Most important Formulas:
Voltage V = I × R = P / I = √(P × R) in volts V
Current I = V / R = P / V = √(P / R) in amperes A
Resistance R = V / I = P / I2 = V2 / P in ohms Ω
Power P = V × I = R × I2 = V2 / R in watts W

Electrical Potential - Ohm's Law
Ohm's law can be expressed as:
V = R I (1a)
V = P / I (1b)
V = (P R)1/2 (1c)
Electric Current - Ohm's Law
I = V / R (2a)
I = P / V (2b)
I = (P / R)1/2 (2c)
Electric Resistance - Ohm's Law
R = V / I (3a)
R = V2/ P (3b)
R = P / I2 (3c)
Electric Power
P = V I (4a)
P = R I2 (4b)
P = V2/ R (4c)
where
P = power (watts, W), V = voltage (volts, V)
I = current (amperes, A), R = resistance (ohms, Ω)
Electric Energy :Electric energy is power multiplied time, or
W = P t (5)
where
W = energy (Ws, J), t = time (s)
Electrical Motors : Electrical Motor Efficiency
μ = 746 Php / Pinput_w (6)
where
μ = efficiency
Php = output horsepower (hp)
Pinput_w = input electrical power (watts)
or alternatively
μ = 746 Php / (1.732 V I PF) (6b)
Electrical Motor - Power
P3-phase = (V I PF 1.732) / 1,000 (7)
where
P3-phase = electrical power 3-phase motor (kW)
PF = power factor electrical motor
Electrical Motor - Amps
I3-phase = (746 Php) / (1.732 V μ PF) (7)
where
I3-phase = electrical current 3-phase motor (amps)
PF = power factor electrical motor
Electrical measurements
Quantity
Name
Definition
frequency f
hertz (Hz)
1/s
force F
newton (N)
kg•m/s²
pressure p
pascal (Pa) = N/m²
kg/m•s²
energy E
work joule (J) = N•m
kg•m²/s²
power P
watt (W) = J/s
kg•m²/s³
electric charge Q
coulomb (C) = A•s
A•s
voltage V
volt (V)= W/A
kg•m²/A•s³
current I
ampere (A) = Q/s
A
capacitance C
farad (F) = C/V = A•s/V = s/Ω
A²•s4/kg•m²
Volt - unit of electrical potential or motive force - potential is required to send one ampere of current through one ohm of resistance
Ohm - unit of resistance - one ohm is the resistance offered to the passage of one ampere when impelled by one volt
Ampere - units of current - one ampere is the current which one volt can send through a resistance of one ohm
Watt - unit of electrical energy or power - one watt is the product of one ampere and one volt - one ampere of current flowing under the force of one volt gives one watt of energy
Volt-ampere (VA) - is a measurement of power in a direct current ( DC ) electrical circuit. The VA specification is also used in alternating current ( AC ) circuits, but it is less precise in this application, because it represents apparent power , which often differs from true power .
Kilovolt Ampere - one kilovolt ampere - KVA - is equal to 1000 volt amperes
Power Factor - ratio of watts to volt amperes
Most important Formulas:
Voltage V = I × R = P / I = √(P × R) in volts V
Current I = V / R = P / V = √(P / R)
in amperes A
Resistance R = V / I = P / I2 = V2 / P in ohms Ω
Power P = V × I = R × I2 = V2 / R in watts W

Electrical Potential - Ohm's Law
Ohm's law can be expressed as:
V = R I (1a)
V = P / I (1b)
V = (P R)1/2 (1c)
Electric Current - Ohm's Law
I = V / R (2a)
I = P / V (2b)
I = (P / R)1/2 (2c)
Electric Resistance - Ohm's Law
R = V / I (3a)
R = V2/ P (3b)
R = P / I2 (3c)
Electric Power
P = V I (4a)
P = R I2 (4b)
P = V2/ R (4c)
where
P = power (watts, W), V = voltage (volts, V)
I = current (amperes, A), R = resistance (ohms, Ω)
Electric Energy :Electric energy is power multiplied time, or
W = P t (5)
where
W = energy (Ws, J), t = time (s)
Electrical Motors : Electrical Motor Efficiency
μ = 746 Php / Pinput_w (6)
where
μ = efficiency
Php = output horsepower (hp)
Pinput_w = input electrical power (watts)
or alternatively
μ = 746 Php / (1.732 V I PF) (6b)
Electrical Motor - Power
P3-phase = (V I PF 1.732) / 1,000 (7)
where
P3-phase = electrical power 3-phase motor (kW)
PF = power factor electrical motor
Electrical Motor - Amps
I3-phase = (746 Php) / (1.732 V μ PF) (7)
where
I3-phase = electrical current 3-phase motor (amps)
PF = power factor electrical motor
Electrical measurements
Quantity
Name
Definition
frequency f
hertz (Hz)
1/s
force F
newton (N)
kg•m/s²
pressure p
pascal (Pa) = N/m²
kg/m•s²
energy E
work joule (J) = N•m
kg•m²/s²
power P
watt (W) = J/s
kg•m²/s³
electric charge Q
coulomb (C) = A•s
A•s
voltage V
volt (V)= W/A
kg•m²/A•s³
current I
ampere (A) = Q/s
A
capacitance C
farad (F) = C/V = A•s/V = s/Ω
A²•s4/kg•m²
Resistance R = V / I = P / I2 = V2 / P in ohms Ω
Power P = V × I = R × I2 = V2 / R in watts W

Electrical Potential - Ohm's Law
Ohm's law can be expressed as:
V = R I (1a)
V = P / I (1b)
V = (P R)1/2 (1c)
Electric Current - Ohm's Law
I = V / R (2a)
I = P / V (2b)
I = (P / R)1/2 (2c)
Electric Resistance - Ohm's Law
R = V / I (3a)
R = V2/ P (3b)
R = P / I2 (3c)
Electric Power
P = V I (4a)
P = R I2 (4b)
P = V2/ R (4c)
where
P = power (watts, W), V = voltage (volts, V)
I = current (amperes, A), R = resistance (ohms, Ω)
Electric Energy :Electric energy is power multiplied time, or
W = P t (5)
where
W = energy (Ws, J), t = time (s)
Electrical Motors : Electrical Motor Efficiency
μ = 746 Php / Pinput_w (6)
where
μ = efficiency
Php = output horsepower (hp)
Pinput_w = input electrical power (watts)
or alternatively
μ = 746 Php / (1.732 V I PF) (6b)
Electrical Motor - Power
P3-phase = (V I PF 1.732) / 1,000 (7)
where
P3-phase = electrical power 3-phase motor (kW)
PF = power factor electrical motor
Electrical Motor - Amps
I3-phase = (746 Php) / (1.732 V μ PF) (7)
where
I3-phase = electrical current 3-phase motor (amps)
PF = power factor electrical motor
Electrical measurements
Quantity
Name
Definition
frequency f
hertz (Hz)
1/s
force F
newton (N)
kg•m/s²
pressure p
pascal (Pa) = N/m²
kg/m•s²
energy E
work joule (J) = N•m
kg•m²/s²
power P
watt (W) = J/s
kg•m²/s³
electric charge Q
coulomb (C) = A•s
A•s
voltage V
volt (V)= W/A
kg•m²/A•s³
current I
ampere (A) = Q/s
A
capacitance C
farad (F) = C/V = A•s/V = s/Ω
A²•s4/kg•m²
Power Factor Correction Equipment: advantages and disadvantages
Normally, the power factor of the whole load on a large generating station is in the region of 0•8 to 0•9. However, sometimes it is lower and in such cases it is generally desirable to take special steps to improve the power factor. This can be achieved by the following equipment:
Static capacitor
The power factor can be improved by connecting capacitors in parallel with the equipment operating at lagging power factor. The capacitor (generally known as static capacitor) draws a leading current and partly or completely neutralizes the lagging reactive component of load current. This raises the power factor of the load. For three-phase loads, the capacitors can be connected in delta or star.
Advantages
They have low losses
They require little maintenance as there are no rotating parts
They can be easily installed as they are light and require no foundation
They can work under ordinary atmospheric conditions
Disadvantages
They have short service life ranging from 8 to 10 years
They are easily damaged if the voltage exceeds the rated value
Once the capacitors are damaged, their repair is uneconomical
Synchronous condenser
A synchronous motor takes a leading current when over-excited and, therefore, behaves as a capacitor. An over-excited synchronous motor running on no load is known as synchronous condenser. When such a machine is connected in parallel with the supply, it takes a leading current which partly neutralizes the lagging reactive component of the load. Thus the power factor is improved.
Advantages
By varying the field excitation, the magnitude of current drawn by the motor can be changed
by any amount. This helps in achieving step less †control of power factor
The motor windings have high thermal stability to short circuit currents
The faults can be removed easily
Disadvantages
There are considerable losses in the motor
The maintenance cost is high
It produces noise
Except in sizes above 500 kVA, the cost is greater than that of static capacitors of the same
rating
As a synchronous motor has no self-starting torque, therefore, an auxiliary equipment has to
be provided for this purpose
Phase advancers
Phase advancers are used to improve the power factor of induction motors. The low power factor of an induction motor is due to the fact that its stator winding draws exciting current which lags be-hind the supply voltage by 90 degrees. If the exciting ampere turns can be provided from some other a.c. source, then the stator winding will be relieved of exciting current and the power factor of the motor can be improved. This job is accomplished by the phase advancer which is simply an a.c. exciter. The phase advancer is mounted on the same shaft as the main motor and is connected in the rotor circuit of the motor. It provides exciting ampere turns to the rotor circuit at slip frequency. By providing more ampere turns than required, the induction motor can be made to operate on leading power factor like an over-excited synchronous motor.
Advantages
As the exciting ampere turns are sup-plied at slip frequency, therefore, lagging kVAR drawn by the motor are considerably reduced
The phase advancer can be conveniently used where the use of synchronous motors is inadmissible
However, the major disadvantage of phase advancers is that they are not economical for motors below 200 H.P
Normally, the power factor of the whole load on a large generating station is in the region of 0•8 to 0•9. However, sometimes it is lower and in such cases it is generally desirable to take special steps to improve the power factor. This can be achieved by the following equipment:
Static capacitor
The power factor can be improved by connecting capacitors in parallel with the equipment operating at lagging power factor. The capacitor (generally known as static capacitor) draws a leading current and partly or completely neutralizes the lagging reactive component of load current. This raises the power factor of the load. For three-phase loads, the capacitors can be connected in delta or star.
Advantages
They have low losses
They require little maintenance as there are no rotating parts
They can be easily installed as they are light and require no foundation
They can work under ordinary atmospheric conditions
Disadvantages
They have short service life ranging from 8 to 10 years
They are easily damaged if the voltage exceeds the rated value
Once the capacitors are damaged, their repair is uneconomical
Synchronous condenser
A synchronous motor takes a leading current when over-excited and, therefore, behaves as a capacitor. An over-excited synchronous motor running on no load is known as synchronous condenser. When such a machine is connected in parallel with the supply, it takes a leading current which partly neutralizes the lagging reactive component of the load. Thus the power factor is improved.
Advantages
By varying the field excitation, the magnitude of current drawn by the motor can be changed
by any amount. This helps in achieving step less †control of power factor
The motor windings have high thermal stability to short circuit currents
The faults can be removed easily
Disadvantages
There are considerable losses in the motor
The maintenance cost is high
It produces noise
Except in sizes above 500 kVA, the cost is greater than that of static capacitors of the same
rating
As a synchronous motor has no self-starting torque, therefore, an auxiliary equipment has to
be provided for this purpose
Phase advancers
Phase advancers are used to improve the power factor of induction motors. The low power factor of an induction motor is due to the fact that its stator winding draws exciting current which lags be-hind the supply voltage by 90 degrees. If the exciting ampere turns can be provided from some other a.c. source, then the stator winding will be relieved of exciting current and the power factor of the motor can be improved. This job is accomplished by the phase advancer which is simply an a.c. exciter. The phase advancer is mounted on the same shaft as the main motor and is connected in the rotor circuit of the motor. It provides exciting ampere turns to the rotor circuit at slip frequency. By providing more ampere turns than required, the induction motor can be made to operate on leading power factor like an over-excited synchronous motor.
Advantages
As the exciting ampere turns are sup-plied at slip frequency, therefore, lagging kVAR drawn by the motor are considerably reduced
The phase advancer can be conveniently used where the use of synchronous motors is inadmissible
However, the major disadvantage of phase advancers is that they are not economical for motors below 200 H.P
What is a bilateral element
Suppose, an electrical element is connected with a voltage source. In case of a bilateral element, if any change occurred in the polarity of the applied voltage, the magnitude of the current passing through the element is not affected by that polarity change.
Lets make it simpler. Think " a " terminal is the positive terminal & terminal " b " is negative terminal of any voltage source. If the legs of a bilateral element altered their position, then the current through it will not affected.
Think about a simple resistor, which is connected with a voltage source. If somehow the polarity is changed, that is the (+) & (−) terminal interchanged, then the current passing through it does not affected, that is the resistor still in same working condition.
A important feature of the bilateral element is, it offers the same impedance irrespective of direction of flow of current. A resistor or a light bulb is the example of bilateral element.
------------------------------
#كهرباء #اتصالات #ميكانيك #it
@mc4eng_2
Suppose, an electrical element is connected with a voltage source. In case of a bilateral element, if any change occurred in the polarity of the applied voltage, the magnitude of the current passing through the element is not affected by that polarity change.
Lets make it simpler. Think " a " terminal is the positive terminal & terminal " b " is negative terminal of any voltage source. If the legs of a bilateral element altered their position, then the current through it will not affected.
Think about a simple resistor, which is connected with a voltage source. If somehow the polarity is changed, that is the (+) & (−) terminal interchanged, then the current passing through it does not affected, that is the resistor still in same working condition.
A important feature of the bilateral element is, it offers the same impedance irrespective of direction of flow of current. A resistor or a light bulb is the example of bilateral element.
------------------------------
#كهرباء #اتصالات #ميكانيك #it
@mc4eng_2
Discuss about the electric potential
Actually this word 'potential' refers to the ability to do some work. So, consider a unit charge (may be positive or negative) is present in an electric field. Now if the charge is positive then a force exerted on it and if the charge is moving towards the field, then both of the forces will be acting in the same direction which is analogical with a mass influenced by the gravity. On the other hand if the charge is negative and is moving in the electric field then this movement will be against the force of the electric field. So we can see that in both the cases work is done (both positive and negative). This work done by the charge while moving in an electric field can be termed as electric potential.
More conventionally the definition of electric potential can be given as the work done needed to move a charge particle from one point to another point in the presence of an electric field. The potential is measured between the two points. The unit of representing electric potential is volt.
From another point of view electric potential can be said as the difference of charge between two points in an electric field or in a coil or circuit.
📚المكتبة الهندسية📚
@mc4eng_books
Actually this word 'potential' refers to the ability to do some work. So, consider a unit charge (may be positive or negative) is present in an electric field. Now if the charge is positive then a force exerted on it and if the charge is moving towards the field, then both of the forces will be acting in the same direction which is analogical with a mass influenced by the gravity. On the other hand if the charge is negative and is moving in the electric field then this movement will be against the force of the electric field. So we can see that in both the cases work is done (both positive and negative). This work done by the charge while moving in an electric field can be termed as electric potential.
More conventionally the definition of electric potential can be given as the work done needed to move a charge particle from one point to another point in the presence of an electric field. The potential is measured between the two points. The unit of representing electric potential is volt.
From another point of view electric potential can be said as the difference of charge between two points in an electric field or in a coil or circuit.
📚المكتبة الهندسية📚
@mc4eng_books
What is electrical potential ?
Whenever a piece of mass is lifted above the ground level, against gravity, some work is to be done. The quantity of work is done, due to this lifting, is the product of gravitational force on the mass and the height the mass has been lifted. This work done, is added in the potential energy of the mass.
Now think about an electrical charge which is entered in an electric field. As per nature of the charge, it will be attracted or repelled by the field. When the charge will move in the electric field, the work will be done against or by the electric force acting on the charge. So there must be some potential energy gained or lost due to this movement. Hence potential in an electric field is exactly the same as potential in the gravitational field.
So potential at any point in an electrical field, is the work done due to movement of a unit positive charge to that point from infinitely long distance.
The potential difference of two points in an electric field is defined as the net work to be done for moving one unit positive charge from lower potential to the higher potential point.
What is the unit of electrical potential difference?
If the unit of charge in the above definition is taken as one Coulomb and the work done, is one Joule for bringing this one Coulomb charge from one point to another, then the potential difference of these two points is considered as unity and it is denoted as one Volt.
If work done in bringing a positive charge of one coulomb from one point to another in an electric field is one joule, then the potential difference between the said points is considered as one Volt.
📚المكتبة الهندسية📚
@mc4eng_books
Whenever a piece of mass is lifted above the ground level, against gravity, some work is to be done. The quantity of work is done, due to this lifting, is the product of gravitational force on the mass and the height the mass has been lifted. This work done, is added in the potential energy of the mass.
Now think about an electrical charge which is entered in an electric field. As per nature of the charge, it will be attracted or repelled by the field. When the charge will move in the electric field, the work will be done against or by the electric force acting on the charge. So there must be some potential energy gained or lost due to this movement. Hence potential in an electric field is exactly the same as potential in the gravitational field.
So potential at any point in an electrical field, is the work done due to movement of a unit positive charge to that point from infinitely long distance.
The potential difference of two points in an electric field is defined as the net work to be done for moving one unit positive charge from lower potential to the higher potential point.
What is the unit of electrical potential difference?
If the unit of charge in the above definition is taken as one Coulomb and the work done, is one Joule for bringing this one Coulomb charge from one point to another, then the potential difference of these two points is considered as unity and it is denoted as one Volt.
If work done in bringing a positive charge of one coulomb from one point to another in an electric field is one joule, then the potential difference between the said points is considered as one Volt.
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@mc4eng_books
What is the difference between emf and potential difference?
As per the definition the emf or the electromotive force describes the force required to separate two charges at a given distance. Originally, emf was supposed to relate to problems involving moving charges, but early on, emf got adopted as being synonymous with "battery" or "voltage source".
Potential difference is simply a voltage difference between two points in a closed electrical circuit with a voltage source circuit (or in free space). So, the interesting fact is the potential difference can be a source of emf if it is used to move charges. The term ‘potential difference’ is a general term and found in all the energy fields such as electric, magnetic and gravitational fields. But emf is only pertaining to electrical circuits. Although, both ‘electrical potential difference’ and emf are measured in Volts (V), there are many differences between them.
Potential Difference
Potential is a function of the location, and potential difference between point A and point B is calculated by subtracting the potential of A from potential of B. In an electric field, it is the amount work to be done to move a unit charge (+1 Coulomb) from B to A. Electric potential difference is measured in V (Volts). In an electrical circuit, current flows from the higher potential to lower potential.
EMF (Electromotive Force)
EMF is the electrical potential difference provided by an energy source like battery. Varying magnetic fields also can generate an EMF according to the Faraday’s law. Although EMF is also a voltage and measured in Volts (V), it is all about the generation of a potential difference.
So the important differences between Voltage and EMF is:
The term ‘potential difference’ is used in all energy fields (electric, magnetic, gravitational), and ‘EMF’ is only used in electric circuits.EMF is the electrical potential difference generated by a source like battery or generator.We can measure potential difference between any two points, but EMF exists only between the two ends of a source.Sum of ‘potential drops’ around a circuit is equal to total EMF according to Kirchhoff’s second law.
📚المكتبة الهندسية📚
@mc4eng_books
As per the definition the emf or the electromotive force describes the force required to separate two charges at a given distance. Originally, emf was supposed to relate to problems involving moving charges, but early on, emf got adopted as being synonymous with "battery" or "voltage source".
Potential difference is simply a voltage difference between two points in a closed electrical circuit with a voltage source circuit (or in free space). So, the interesting fact is the potential difference can be a source of emf if it is used to move charges. The term ‘potential difference’ is a general term and found in all the energy fields such as electric, magnetic and gravitational fields. But emf is only pertaining to electrical circuits. Although, both ‘electrical potential difference’ and emf are measured in Volts (V), there are many differences between them.
Potential Difference
Potential is a function of the location, and potential difference between point A and point B is calculated by subtracting the potential of A from potential of B. In an electric field, it is the amount work to be done to move a unit charge (+1 Coulomb) from B to A. Electric potential difference is measured in V (Volts). In an electrical circuit, current flows from the higher potential to lower potential.
EMF (Electromotive Force)
EMF is the electrical potential difference provided by an energy source like battery. Varying magnetic fields also can generate an EMF according to the Faraday’s law. Although EMF is also a voltage and measured in Volts (V), it is all about the generation of a potential difference.
So the important differences between Voltage and EMF is:
The term ‘potential difference’ is used in all energy fields (electric, magnetic, gravitational), and ‘EMF’ is only used in electric circuits.EMF is the electrical potential difference generated by a source like battery or generator.We can measure potential difference between any two points, but EMF exists only between the two ends of a source.Sum of ‘potential drops’ around a circuit is equal to total EMF according to Kirchhoff’s second law.
📚المكتبة الهندسية📚
@mc4eng_books
Passive and active elements of electric circuit
A branch of electrical network which dose not contain any source, is generally referred as passive branch. The passive branch may consist of resistors, capacitors and inductors and other elements which are not sources of energy. These type of network elements which are not associated with energy source, are called passive element. Hence, passive branch of a network consists only passive elements or components.
A branch of electrical network, consists of at least one active element, is called active branch. Active elements of a network are those which supply energy in the network. The network branch consists at least one active element may be along with other passive component, is an active branch.
Suppose one 1.5 V battery connected with one 2 ohms resistance in series. One LED with a shunt resistance is connected across the series combination of battery and resistance. Here, the branch formed by LED & shunt resistor is referred as passive branch since it does not contain any active element. As the battery is an electrical energy source, it is an active element. Thus that branch of the said network, which contains the battery along with the 2 ohms resistor is called active branch of the network.
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@mc4eng_books
A branch of electrical network which dose not contain any source, is generally referred as passive branch. The passive branch may consist of resistors, capacitors and inductors and other elements which are not sources of energy. These type of network elements which are not associated with energy source, are called passive element. Hence, passive branch of a network consists only passive elements or components.
A branch of electrical network, consists of at least one active element, is called active branch. Active elements of a network are those which supply energy in the network. The network branch consists at least one active element may be along with other passive component, is an active branch.
Suppose one 1.5 V battery connected with one 2 ohms resistance in series. One LED with a shunt resistance is connected across the series combination of battery and resistance. Here, the branch formed by LED & shunt resistor is referred as passive branch since it does not contain any active element. As the battery is an electrical energy source, it is an active element. Thus that branch of the said network, which contains the battery along with the 2 ohms resistor is called active branch of the network.
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@mc4eng_books
What is a linear element
In an electrical network, a linear element shows the linear characteristics in between voltage & current. That is the current passing through a linear element is changed according to the change in the voltage across its terminals.
An important phenomenon of any linear element is the properties of the linear element do not change with the change of applied voltage or the circuit current. Resistors, inductors, capacitors are linear elements as their resistances, inductances, capacitances do not change with a change in applied voltage or the circuit current.
A circuit which is made with only linear elements, is called linear network. Sometime this type of circuit is very useful where voltage versus current relationship should remain linear & any signal distortion is not required.
📚المكتبة الهندسية📚
@mc4eng_books
In an electrical network, a linear element shows the linear characteristics in between voltage & current. That is the current passing through a linear element is changed according to the change in the voltage across its terminals.
An important phenomenon of any linear element is the properties of the linear element do not change with the change of applied voltage or the circuit current. Resistors, inductors, capacitors are linear elements as their resistances, inductances, capacitances do not change with a change in applied voltage or the circuit current.
A circuit which is made with only linear elements, is called linear network. Sometime this type of circuit is very useful where voltage versus current relationship should remain linear & any signal distortion is not required.
📚المكتبة الهندسية📚
@mc4eng_books
What is a nonlinear element?
In an electrical network, a non-linear shows the non-linear characteristics in between voltage & current. More specifically, in case of a non-linear element the current passing through it does not change linearly with the linear change in applied voltage at a particular frequency.
An important phenomenon of any non-linear element is they can can distort a given signal. As, they shows non-linear characteristics in between voltage & current so, their current versus voltage curve is not a straight line.
As a instance, we can say a transistor is a non-linear element as the current through it is a non-linear function of the voltage across its terminals. Actually, vacuum tubes, semiconductor devices like diodes, transistors are the non-linear elements.
------------------------------
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@mc4eng_2
In an electrical network, a non-linear shows the non-linear characteristics in between voltage & current. More specifically, in case of a non-linear element the current passing through it does not change linearly with the linear change in applied voltage at a particular frequency.
An important phenomenon of any non-linear element is they can can distort a given signal. As, they shows non-linear characteristics in between voltage & current so, their current versus voltage curve is not a straight line.
As a instance, we can say a transistor is a non-linear element as the current through it is a non-linear function of the voltage across its terminals. Actually, vacuum tubes, semiconductor devices like diodes, transistors are the non-linear elements.
------------------------------
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@mc4eng_2
What is a unilateral element ?
Suppose, an electrical element is connected with a voltage source. If the element is unilateral, then whenever there is a change is occurred in the polarity of the applied voltage, that is the positive & negative terminal of the source altered, the magnitude of the current passing through the element is affected by the polarity change.
Think about a simple diode, which is connected with a voltage source. If somehow the polarity is changed, that is the (+) & (−) terminal interchanged, then the diode will not work. So, we can say, diode is an unilateral element. A important feature of an unilateral element is, it offer varying impedances with variations in flow of current.
Basically, semiconductor devices like diodes, transistors, operational amplifiers are the unilateral element.
------------------------------
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@mc4eng_2
Suppose, an electrical element is connected with a voltage source. If the element is unilateral, then whenever there is a change is occurred in the polarity of the applied voltage, that is the positive & negative terminal of the source altered, the magnitude of the current passing through the element is affected by the polarity change.
Think about a simple diode, which is connected with a voltage source. If somehow the polarity is changed, that is the (+) & (−) terminal interchanged, then the diode will not work. So, we can say, diode is an unilateral element. A important feature of an unilateral element is, it offer varying impedances with variations in flow of current.
Basically, semiconductor devices like diodes, transistors, operational amplifiers are the unilateral element.
------------------------------
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@mc4eng_2
NETWORK THEOREMS –
1. Kirchhoff s current law states that
(a) net current flow at the junction is positive
(b) Hebraic sum of the currents meeting at the junction is zero
(c) no current can leave the junction without some current entering it.
(d) total sum of currents meeting at the junction is zero
Ans: b
2. According to Kirchhoffs voltage law, the algebraic sum of all IR drops and
e.m.fs. in any closed loop of a network is always
(a) negative
(b) positive
(c) determined by battery e.m.fs.
(d) zero
Ans: d
3. Kirchhoffs current law is applicable to only
(a) junction in a network
(b) closed loops in a network
(c) electric circuits
(d) electronic circuits
Ans: a
4. Kirchhoffs voltage law is related to
(a) junction currents
(b) battery e.m.fs.
(c) IR drops
(d) both (b) and (c)
(e) none of the above
Ans: d
5. Superposition theorem can be applied only to circuits having
(a) resistive elements
(b) passive elements
(c) non-linear elements
(d) linear bilateral elements
Ans: d
6. The concept on which Superposition theorem is based is
(a) reciprocity
(b) duality
(c) non-linearity
(d) linearity
Ans: d
7. Thevenin resistance Rth is found
(a) by removing voltage sources along with their internal resistances
(6) by short-circuiting the given two terminals
(c) between any two ‘open’ terminals
(d) between same open terminals as for Etk
Ans: d
8. An ideal voltage source should have
(a) large value of e.m.f.
(b) small value of e.m.f.
(c) zero source resistance
(d) infinite source resistance
Ans: c
9. For a voltage source
(a) terminal voltage is always lower than source e.m.f.
(b) terminal voltage cannot be higher than source e.m.f.
(c) the source e.m.f. and terminal voltage are equal
Ans: b
10. To determine the polarity of the voltage drop across a resistor, it is necessary
to know
(a) value of current through the resistor
(b) direction of current through the resistor
(c) value of resistor
(d) e.m.fs. in the circuit
Ans: b
11. “Maximum power output is obtained from a network when the load resistance
is equal to the output resistance of the network as seen from the terminals of the
load”. The above statement is associated with
(a) Millman’s theorem
(b) Thevenin’s theorem
(c) Superposition theorem
(d) Maximum power transfer theorem
Ans: d
12. “Any number of current sources in parallel may be replaced by a single current
source whose current is the algebraic sum of individual source currents and
source resistance is the parallel combination of individual
source resistances”. The above statement is associated with
(a) Thevenin’s theorem
(b) Millman’s theorem
(c) Maximum power transfer theorem
(d) None of the above
Ans: b
13. “In any linear bilateral network, if a source of e.m.f. E in any branch produces
a current I in any other
branch, then same e.m.f. acting in the second branch would produce the same
current / in the first branch”. The above statement is associated with
(a) compensation theorem
(b) superposition theorem
(c) reciprocity theorem
(d) none of the above
Ans: c
14. Which of the following is non-linear circuit parameter ?
(a) Inductance
(b) Condenser
(c) Wire wound resistor
(d) Transistor
Ans: a
15. A capacitor is generally a
(a) bilateral and active component
(b) active, passive, linear and nonlinear component
(c) linear and bilateral component
(d) non-linear and active component
Ans: c
16. “In any network containing more than one sources of e.m.f. the current in any
branch is the algebraic sum of a number of individual fictitious currents (the
number being equal to the number of sources of e.m.f.), each of which is due to
separate action of each source of e.m.f., taken in order, when the remaining
sources of e.m.f. are replaced by conductors, the resistances of which are equal to
the internal resistances of the respective sources”. The above statement is associated with
(a) Thevenin’s theorem
(b) Norton’s theorem
(c) Superposition theorem
(d) None of the above
Ans: c
17. Kirchhoff s law is applicable to
(a) passive netw
1. Kirchhoff s current law states that
(a) net current flow at the junction is positive
(b) Hebraic sum of the currents meeting at the junction is zero
(c) no current can leave the junction without some current entering it.
(d) total sum of currents meeting at the junction is zero
Ans: b
2. According to Kirchhoffs voltage law, the algebraic sum of all IR drops and
e.m.fs. in any closed loop of a network is always
(a) negative
(b) positive
(c) determined by battery e.m.fs.
(d) zero
Ans: d
3. Kirchhoffs current law is applicable to only
(a) junction in a network
(b) closed loops in a network
(c) electric circuits
(d) electronic circuits
Ans: a
4. Kirchhoffs voltage law is related to
(a) junction currents
(b) battery e.m.fs.
(c) IR drops
(d) both (b) and (c)
(e) none of the above
Ans: d
5. Superposition theorem can be applied only to circuits having
(a) resistive elements
(b) passive elements
(c) non-linear elements
(d) linear bilateral elements
Ans: d
6. The concept on which Superposition theorem is based is
(a) reciprocity
(b) duality
(c) non-linearity
(d) linearity
Ans: d
7. Thevenin resistance Rth is found
(a) by removing voltage sources along with their internal resistances
(6) by short-circuiting the given two terminals
(c) between any two ‘open’ terminals
(d) between same open terminals as for Etk
Ans: d
8. An ideal voltage source should have
(a) large value of e.m.f.
(b) small value of e.m.f.
(c) zero source resistance
(d) infinite source resistance
Ans: c
9. For a voltage source
(a) terminal voltage is always lower than source e.m.f.
(b) terminal voltage cannot be higher than source e.m.f.
(c) the source e.m.f. and terminal voltage are equal
Ans: b
10. To determine the polarity of the voltage drop across a resistor, it is necessary
to know
(a) value of current through the resistor
(b) direction of current through the resistor
(c) value of resistor
(d) e.m.fs. in the circuit
Ans: b
11. “Maximum power output is obtained from a network when the load resistance
is equal to the output resistance of the network as seen from the terminals of the
load”. The above statement is associated with
(a) Millman’s theorem
(b) Thevenin’s theorem
(c) Superposition theorem
(d) Maximum power transfer theorem
Ans: d
12. “Any number of current sources in parallel may be replaced by a single current
source whose current is the algebraic sum of individual source currents and
source resistance is the parallel combination of individual
source resistances”. The above statement is associated with
(a) Thevenin’s theorem
(b) Millman’s theorem
(c) Maximum power transfer theorem
(d) None of the above
Ans: b
13. “In any linear bilateral network, if a source of e.m.f. E in any branch produces
a current I in any other
branch, then same e.m.f. acting in the second branch would produce the same
current / in the first branch”. The above statement is associated with
(a) compensation theorem
(b) superposition theorem
(c) reciprocity theorem
(d) none of the above
Ans: c
14. Which of the following is non-linear circuit parameter ?
(a) Inductance
(b) Condenser
(c) Wire wound resistor
(d) Transistor
Ans: a
15. A capacitor is generally a
(a) bilateral and active component
(b) active, passive, linear and nonlinear component
(c) linear and bilateral component
(d) non-linear and active component
Ans: c
16. “In any network containing more than one sources of e.m.f. the current in any
branch is the algebraic sum of a number of individual fictitious currents (the
number being equal to the number of sources of e.m.f.), each of which is due to
separate action of each source of e.m.f., taken in order, when the remaining
sources of e.m.f. are replaced by conductors, the resistances of which are equal to
the internal resistances of the respective sources”. The above statement is associated with
(a) Thevenin’s theorem
(b) Norton’s theorem
(c) Superposition theorem
(d) None of the above
Ans: c
17. Kirchhoff s law is applicable to
(a) passive netw
orks only
(b) a.c. circuits only
(c) d.c. circuits only
(d) both a.c. as well d.c. circuits
Ans: d
18. Kirchhoff s law is not applicable to circuits with
(a) lumped parameters
(b) passive elements
(c) distributed parameters
(d) non-linear resistances
Ans: c
19. Kirchhoff s voltage law applies to circuits with
(a) nonlinear elements only
(b) linear elements only
(c) linear, non-linear, active and passive elements
(d) linear, non-linear, active, passive, time varying as wells as time-in-variant
elements
Ans: d
20. The resistance LM will be
(a) 6.66 Q
(b) 12 Q
(c) 18Q
(d) 20Q
Ans: a
21. For high efficiency of transfer of power, internal resistance of the source
should be
(a) equal to the load resistance
(b) less than the load resistance
(c) more than the load resistance
(d) none of the above
Ans: b
22. Efficiency of power transfer when maximum transfer of power c xerosis
(a) 100%
(b) 80%
(c) 75%
(d) 50%
Ans: d
23. If resistance across LM in Fig. 2.30 is 15 ohms, the value of R is
(a) 10 Q
(6) 20 Q
(c) 30 Q
(d) 40 Q
Ans: c
24. For maximum transfer of power, internal resistance of the source should be
(a) equal to load resistance
(b) less than the load resistance
(c) greater than the load resistance
(d) none of the above
Ans: a
25. If the energy is supplied from a source, whose resistance is 1 ohm, to a load of
100 ohms the source will be
(a) a voltage source
(b) a current source
(c) both of above
(d) none of the above
Ans: a
26. The circuit whose properties are same in either direction is known as
(a) unilateral circuit
(b) bilateral circuit
(c) irreversible circuit
(d) reversible circuit
Ans: b
27. In a series parallel circuit, any two resistances in the same current path must
be in
(a) series with each other
(b) parallel with each other
(c) series with the voltage source.’
(d) parallel with the voltage source
Ans: a
28. The circuit has resistors, capacitors and semi-conductor diodes. The circuit
will be known as
(a) non-linear circuit
(b) linear circuit
(c) bilateral circuit
(d) none of the above
Ans: a
29. A non-linear network does not satisfy
(a) superposition condition
(b) homogeneity condition
(c) both homogeneity as well as superposition condition
(d) homogeneity, superposition and associative condition
Ans: c
30. An ideal voltage source has
(a) zero internal resistance
(b) open circuit voltage equal to the voltage on full load
(c) terminal voltage in proportion to current
(d) terminal voltage in proportion to load
Ans: a
31. A network which contains one or more than one source of e.m.f. is known as
(a) linear network
(b) non-linear network
(c) passive network
(d) active network
Ans: c
32. The superposition theorem is applicable to
(a) linear, non-linear and time variant responses
(b) linear and non-linear resistors only
(c) linear responses only
(d) none of the above
Ans: c
33. Which of the following is not a nonlinear element ?
(a) Gas diode
(b) Heater coil
(c) Tunnel diode
(d) Electric arc
Ans:
34. Application of Norton’s theorem to a circuit yields
(a) equivalent current source and impedance in series
(6) equivalent current source and impedance in parallel
(c) equivalent impedance
(d) equivalent current source
Ans: a
35. Millman’s theorem yields
(a) equivalent resistance
(6) equivalent impedance
(c) equivalent voltage source
(d) equivalent voltage or current source
Ans: d
36. The superposition theorem is applicable to
(a) voltage only
(b) current “only
(c) both current and voltage
(d) current voltage and power
Ans: d
37. Between the branch voltages of a loop the Kirchhoff s voltage law imposes
(a) non-linear constraints
(b) linear constraints
(c) no constraints
(d) none of the above
Ans: b a
38. A passive network is one which contains
(a) only variable resistances
(b) only some sources of e.m.f. in it
(c) only two sources of e.m.f. in it
(d) no source of e.m.f. in it
Ans: d
39. A terminal where three on more branches meet is known as
(a) node
(b) terminus
(c) combination
(d) anode
(b) a.c. circuits only
(c) d.c. circuits only
(d) both a.c. as well d.c. circuits
Ans: d
18. Kirchhoff s law is not applicable to circuits with
(a) lumped parameters
(b) passive elements
(c) distributed parameters
(d) non-linear resistances
Ans: c
19. Kirchhoff s voltage law applies to circuits with
(a) nonlinear elements only
(b) linear elements only
(c) linear, non-linear, active and passive elements
(d) linear, non-linear, active, passive, time varying as wells as time-in-variant
elements
Ans: d
20. The resistance LM will be
(a) 6.66 Q
(b) 12 Q
(c) 18Q
(d) 20Q
Ans: a
21. For high efficiency of transfer of power, internal resistance of the source
should be
(a) equal to the load resistance
(b) less than the load resistance
(c) more than the load resistance
(d) none of the above
Ans: b
22. Efficiency of power transfer when maximum transfer of power c xerosis
(a) 100%
(b) 80%
(c) 75%
(d) 50%
Ans: d
23. If resistance across LM in Fig. 2.30 is 15 ohms, the value of R is
(a) 10 Q
(6) 20 Q
(c) 30 Q
(d) 40 Q
Ans: c
24. For maximum transfer of power, internal resistance of the source should be
(a) equal to load resistance
(b) less than the load resistance
(c) greater than the load resistance
(d) none of the above
Ans: a
25. If the energy is supplied from a source, whose resistance is 1 ohm, to a load of
100 ohms the source will be
(a) a voltage source
(b) a current source
(c) both of above
(d) none of the above
Ans: a
26. The circuit whose properties are same in either direction is known as
(a) unilateral circuit
(b) bilateral circuit
(c) irreversible circuit
(d) reversible circuit
Ans: b
27. In a series parallel circuit, any two resistances in the same current path must
be in
(a) series with each other
(b) parallel with each other
(c) series with the voltage source.’
(d) parallel with the voltage source
Ans: a
28. The circuit has resistors, capacitors and semi-conductor diodes. The circuit
will be known as
(a) non-linear circuit
(b) linear circuit
(c) bilateral circuit
(d) none of the above
Ans: a
29. A non-linear network does not satisfy
(a) superposition condition
(b) homogeneity condition
(c) both homogeneity as well as superposition condition
(d) homogeneity, superposition and associative condition
Ans: c
30. An ideal voltage source has
(a) zero internal resistance
(b) open circuit voltage equal to the voltage on full load
(c) terminal voltage in proportion to current
(d) terminal voltage in proportion to load
Ans: a
31. A network which contains one or more than one source of e.m.f. is known as
(a) linear network
(b) non-linear network
(c) passive network
(d) active network
Ans: c
32. The superposition theorem is applicable to
(a) linear, non-linear and time variant responses
(b) linear and non-linear resistors only
(c) linear responses only
(d) none of the above
Ans: c
33. Which of the following is not a nonlinear element ?
(a) Gas diode
(b) Heater coil
(c) Tunnel diode
(d) Electric arc
Ans:
34. Application of Norton’s theorem to a circuit yields
(a) equivalent current source and impedance in series
(6) equivalent current source and impedance in parallel
(c) equivalent impedance
(d) equivalent current source
Ans: a
35. Millman’s theorem yields
(a) equivalent resistance
(6) equivalent impedance
(c) equivalent voltage source
(d) equivalent voltage or current source
Ans: d
36. The superposition theorem is applicable to
(a) voltage only
(b) current “only
(c) both current and voltage
(d) current voltage and power
Ans: d
37. Between the branch voltages of a loop the Kirchhoff s voltage law imposes
(a) non-linear constraints
(b) linear constraints
(c) no constraints
(d) none of the above
Ans: b a
38. A passive network is one which contains
(a) only variable resistances
(b) only some sources of e.m.f. in it
(c) only two sources of e.m.f. in it
(d) no source of e.m.f. in it
Ans: d
39. A terminal where three on more branches meet is known as
(a) node
(b) terminus
(c) combination
(d) anode
Ans: a
40. Which of the following is the passive element ?
(a) Capacitance
(b) Ideal current source
(c) Ideal voltage source
(d) All of the above
Ans: a
41. Which of the following is a bilateral element ?
(a) Constant current source
(b) Constant voltage source
(c) Capacitance
(d) None of the above
Ans: c
42. A closed path made by several branches of the network is known as
(a) branch
(b) loop
(c) circuit
(d) junction
Ans: b
43. A linear resistor having 0 < R < °o is a
(a) current controlled resistor
(6) voltage controlled resistor
(c) both current controlled and voltage controlled resistor
(d) none of the above
Ans: c
44. A star circuit has element of resistance R/2. The equivalent delta elements
will be
(a) R/6
(b) fi?
(c) 2R
(d) 4R
Ans: b
45. A delta circuit has each element of value R/2. The equivalent elements of star
circuit with be
(a) RIG
(b) R/3
(c) 2R
(d) 3R
Ans: a
56. In Thevenin’s theorem, to find Z
(a) all independent current sources are short circuited and independent voltage
sources are open circuited
(b) all independent voltage sources are open circuited and all independent
current sources are short circuited
(c) all independent voltage and current sources are short circuited
(d) all independent voltage sources are short circuited and all independent
current sources are open circuited
Ans: d
57. While calculating Rth in Thevenin’s theorem and Norton equivalent
(a) all independent sources are made dead
(b) only current sources are made dead
(c) only voltage sources are made dead
(d) all voltage and current sources are made dead
Ans: a
58. The number of independent equations to solve a network is equal to
(a) the number of chords
(b) the number of branches
(c) sum of the number of branches and chords
(d) sum of number of branches, chords and nodes
Ans: a
59. The superposition theorem requires as many circuits to be solved as there are
(a) sources, nodes and meshes
(b) sources and nodes
(c) sources
(d) nodes
Ans: c
60. Choose the incorrect statement.
(a) A branch formed by the parallel connection of any resistor R and open circuit
has the characteristic of an open circuit.
(b) A branch formed by the parallel connection of any resistor R and a short
circuit has the characteristic of a short circuit.
(c) A branch formed by the series connection of any resistor R and an open circuit
has the characteristic of an open circuit.
(d) A branch formed by the series connection of any resistor R and a short circuit
has the characteristic of resistor R.
Ans: a
@ElectricalLearner
40. Which of the following is the passive element ?
(a) Capacitance
(b) Ideal current source
(c) Ideal voltage source
(d) All of the above
Ans: a
41. Which of the following is a bilateral element ?
(a) Constant current source
(b) Constant voltage source
(c) Capacitance
(d) None of the above
Ans: c
42. A closed path made by several branches of the network is known as
(a) branch
(b) loop
(c) circuit
(d) junction
Ans: b
43. A linear resistor having 0 < R < °o is a
(a) current controlled resistor
(6) voltage controlled resistor
(c) both current controlled and voltage controlled resistor
(d) none of the above
Ans: c
44. A star circuit has element of resistance R/2. The equivalent delta elements
will be
(a) R/6
(b) fi?
(c) 2R
(d) 4R
Ans: b
45. A delta circuit has each element of value R/2. The equivalent elements of star
circuit with be
(a) RIG
(b) R/3
(c) 2R
(d) 3R
Ans: a
56. In Thevenin’s theorem, to find Z
(a) all independent current sources are short circuited and independent voltage
sources are open circuited
(b) all independent voltage sources are open circuited and all independent
current sources are short circuited
(c) all independent voltage and current sources are short circuited
(d) all independent voltage sources are short circuited and all independent
current sources are open circuited
Ans: d
57. While calculating Rth in Thevenin’s theorem and Norton equivalent
(a) all independent sources are made dead
(b) only current sources are made dead
(c) only voltage sources are made dead
(d) all voltage and current sources are made dead
Ans: a
58. The number of independent equations to solve a network is equal to
(a) the number of chords
(b) the number of branches
(c) sum of the number of branches and chords
(d) sum of number of branches, chords and nodes
Ans: a
59. The superposition theorem requires as many circuits to be solved as there are
(a) sources, nodes and meshes
(b) sources and nodes
(c) sources
(d) nodes
Ans: c
60. Choose the incorrect statement.
(a) A branch formed by the parallel connection of any resistor R and open circuit
has the characteristic of an open circuit.
(b) A branch formed by the parallel connection of any resistor R and a short
circuit has the characteristic of a short circuit.
(c) A branch formed by the series connection of any resistor R and an open circuit
has the characteristic of an open circuit.
(d) A branch formed by the series connection of any resistor R and a short circuit
has the characteristic of resistor R.
Ans: a
@ElectricalLearner
CABLES➡️➡️
1. The insulating material for a cable should have
(a) low cost
(b) high dielectric strength
(c) high mechanical strength
(d) all of the above
Ans: d
2. Which of the following protects a cable against mechanical injury ?
(a) Bedding
(b) Sheath
(c) Armouring
(d) None of the above
Ans: c
3. Which of the following insulation is used in cables ?
(a) Varnished cambric
(b) Rubber
(c) Paper
(d) Any of the above
Ans: d
4. Empire tape is
(a) varnished cambric
(b) vulcanised rubber
(c) impregnated paper
(d) none of the above
Ans: a
5. The thickness of the layer of insulation on the conductor, in cables, depends
upon
(a) reactive power
(b) power factor
(c) voltage
(d) current carrying capacity
Ans: c
6. The bedding on a cable consists of
(a) hessian cloth
(b) jute
(c) any of the above
(d) none of the above
Ans: c
7. The insulating material for cables should
(a) be acid proof
(b) be non-inflammable
(c) be non-hygroscopic
(d) have all above properties
Ans: d
8. In a cable immediately above metallic sheath _ is provided.
(a) earthing connection
(b) bedding
(c) armouring
(d) none of the above
Ans: b
9. The current carrying capacity of cables in D.C. is more thanthat in A.C. mainly
due to
(a) absence of harmonics
(b) non-existence of any stability limit
(c) smaller dielectric loss
(d) absence of ripples
(e) none of the above
Ans: c
10. In case of three core flexible cable the colour of the neutral is
(a) blue
(b) black
(c) brown
(d) none of the above
Ans: a
11 cables are used for 132 kV lines.
(a) High tension
(b) Super tension
(c) Extra high tension
(d) Extra super voltage
Ans: d
12. Conduit pipes are normally used to protect _ cables.
(a) unsheathed cables
(b) armoured
(c) PVC sheathed cables
(d) all of the above
Ans: a
13. The minimum dielectric stress in a cable is at
(a) armour
(b) bedding
(c) conductor surface
(d) lead sheath
Ans: d
14. In single core cables armouring is not done to
(a) avoid excessive sheath losses
(b) make it flexible
(c) either of the above
(d) none of the above
Ans: a
15. Dielectric strength of rubber is around
(a) 5 kV/mm
(b) 15 kV/mm
(c) 30 kV/mm
(d) 200 kV/mm
Ans: c
16. Low tension cables are generally used up to
(a) 200 V
(b) 500 V
(c) 700 V
(d) 1000 V
Ans: d
17. In a cable, the maximum stress under operating conditions is at
(a) insulation layer
(b) sheath
(c) armour
(d) conductor surface
Ans: d
18. High tension cables are generally used up to
(a) 11kV
(b) 33kV
(c) 66 kV
(d) 132 kV
Ans: a
19. The surge resistance of cable is
(a) 5 ohms
(b) 20 ohms
(c) 50 ohms
(d) 100 ohms
Ans: c
20. PVC stands for
(a) polyvinyl chloride
(b) post varnish conductor
(c) pressed and varnished cloth
(d) positive voltage conductor
(e) none of the above
Ans: a
In the cables, the location of fault is usually found out by comparing
(a) the resistance of the conductor
(b) the inductance of conductors
(c) the capacitances of insulated conductors
(d) all above parameters
Ans: c
22. In capacitance grading of cables we use a __ dielectric.
(a) composite
(b) porous
(c) homogeneous
(d) hygroscopic
Ans: a
23. Pressure cables are generally not used beyond
(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 132 kV
Ans: c
24. The material for armouring on cable is usually
(a) steel tape
(b) galvanised steel wire
(c) any of the above
(d) none of the above
Ans: c
25. Cables, generally used beyond 66 kV are
(a) oil filled
(b) S.L. type
(c) belted
(d) armoured
Ans: a
26. The relative permittivity of rubber is
(a) between 2 and 3
(b) between 5 and 6
(c) between 8 and 10
(d) between 12 and 14
Ans: a
27. Solid type cables are considered unreliable beyond 66 kV because
(a) insulation may melt due to higher temperature
(b) skin effect dominates on the conductor
(c) of corona loss between conductor and sheath material
(d) there is a danger of breakdown of insulation due to the presence of voids
Ans: d
28. If the length of a cable is doubled, its capacitance
(a) becomes one-fourth
(b) be
1. The insulating material for a cable should have
(a) low cost
(b) high dielectric strength
(c) high mechanical strength
(d) all of the above
Ans: d
2. Which of the following protects a cable against mechanical injury ?
(a) Bedding
(b) Sheath
(c) Armouring
(d) None of the above
Ans: c
3. Which of the following insulation is used in cables ?
(a) Varnished cambric
(b) Rubber
(c) Paper
(d) Any of the above
Ans: d
4. Empire tape is
(a) varnished cambric
(b) vulcanised rubber
(c) impregnated paper
(d) none of the above
Ans: a
5. The thickness of the layer of insulation on the conductor, in cables, depends
upon
(a) reactive power
(b) power factor
(c) voltage
(d) current carrying capacity
Ans: c
6. The bedding on a cable consists of
(a) hessian cloth
(b) jute
(c) any of the above
(d) none of the above
Ans: c
7. The insulating material for cables should
(a) be acid proof
(b) be non-inflammable
(c) be non-hygroscopic
(d) have all above properties
Ans: d
8. In a cable immediately above metallic sheath _ is provided.
(a) earthing connection
(b) bedding
(c) armouring
(d) none of the above
Ans: b
9. The current carrying capacity of cables in D.C. is more thanthat in A.C. mainly
due to
(a) absence of harmonics
(b) non-existence of any stability limit
(c) smaller dielectric loss
(d) absence of ripples
(e) none of the above
Ans: c
10. In case of three core flexible cable the colour of the neutral is
(a) blue
(b) black
(c) brown
(d) none of the above
Ans: a
11 cables are used for 132 kV lines.
(a) High tension
(b) Super tension
(c) Extra high tension
(d) Extra super voltage
Ans: d
12. Conduit pipes are normally used to protect _ cables.
(a) unsheathed cables
(b) armoured
(c) PVC sheathed cables
(d) all of the above
Ans: a
13. The minimum dielectric stress in a cable is at
(a) armour
(b) bedding
(c) conductor surface
(d) lead sheath
Ans: d
14. In single core cables armouring is not done to
(a) avoid excessive sheath losses
(b) make it flexible
(c) either of the above
(d) none of the above
Ans: a
15. Dielectric strength of rubber is around
(a) 5 kV/mm
(b) 15 kV/mm
(c) 30 kV/mm
(d) 200 kV/mm
Ans: c
16. Low tension cables are generally used up to
(a) 200 V
(b) 500 V
(c) 700 V
(d) 1000 V
Ans: d
17. In a cable, the maximum stress under operating conditions is at
(a) insulation layer
(b) sheath
(c) armour
(d) conductor surface
Ans: d
18. High tension cables are generally used up to
(a) 11kV
(b) 33kV
(c) 66 kV
(d) 132 kV
Ans: a
19. The surge resistance of cable is
(a) 5 ohms
(b) 20 ohms
(c) 50 ohms
(d) 100 ohms
Ans: c
20. PVC stands for
(a) polyvinyl chloride
(b) post varnish conductor
(c) pressed and varnished cloth
(d) positive voltage conductor
(e) none of the above
Ans: a
In the cables, the location of fault is usually found out by comparing
(a) the resistance of the conductor
(b) the inductance of conductors
(c) the capacitances of insulated conductors
(d) all above parameters
Ans: c
22. In capacitance grading of cables we use a __ dielectric.
(a) composite
(b) porous
(c) homogeneous
(d) hygroscopic
Ans: a
23. Pressure cables are generally not used beyond
(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 132 kV
Ans: c
24. The material for armouring on cable is usually
(a) steel tape
(b) galvanised steel wire
(c) any of the above
(d) none of the above
Ans: c
25. Cables, generally used beyond 66 kV are
(a) oil filled
(b) S.L. type
(c) belted
(d) armoured
Ans: a
26. The relative permittivity of rubber is
(a) between 2 and 3
(b) between 5 and 6
(c) between 8 and 10
(d) between 12 and 14
Ans: a
27. Solid type cables are considered unreliable beyond 66 kV because
(a) insulation may melt due to higher temperature
(b) skin effect dominates on the conductor
(c) of corona loss between conductor and sheath material
(d) there is a danger of breakdown of insulation due to the presence of voids
Ans: d
28. If the length of a cable is doubled, its capacitance
(a) becomes one-fourth
(b) be
comes one-half
(c) becomes double
(d) remains unchanged
Ans: c
29. In cables the charging current
(a) lags the voltage by 90°
(b) leads the voltage by 90°
(c) lags the voltage by 180°
(d) leads the voltage by 180° Ans: b
30. A certain cable has an insulation of relative permittivity 4. If the insulation is
replaced by one of relative permittivity 2, the capacitance of the cable will become
(a) one half
(6) double
(c) four times
(d) none of the above
Ans: a
31. If a cable of homogeneous insulation has a maximum stress of 10 kV/mm,
then the dielectric strength of insulation should be
(a) 5 kV/mm
(b) 10 kV/mm
(a) 15 kV/mm
(d) 30 kV/mm
Ans: b
32. In the cables, sheaths are used to
(a) prevent the moisture from entering the cable
(b) provide enough strength
(e) provide proper insulation
(d) none of the above
Ans: a
33. The intersheaths in the cables are used to
(a) minimize the stress
(b) avoid the requirement of good insulation
(c) provide proper stress distribution
(d) none of the above
Ans: c
34. The electrostatic stress in underground cables is
(a) same at the conductor and the sheath
(b) minimum at the conductor and maximum at the sheath
(c) maximum at the conductor and minimum at the sheath
(d) zero at the conductor as well as on the sheath
(e) none of the above
Ans: c
35. The breakdown of insulation of the cable can be avoided economically by the
use of
(a) inter-sheaths
(b) insulating materials with different dielectric constants
(c) both (a) and (b)
(d) none of the above
Ans: c
36. The insulation of the cable decreases with
(a) the increase in length of the insulation
(b) the decrease in the length of the insulation
(c) either (a) or (b)
(d) none of the above
Ans: a
37. A cable carrying alternating current has
(a) hysteresis losses only
(b) hysteresis and leakage losses only
(c) hysteresis, leakage and copper losses only
(d) hysteresis, leakage, copper and friction losses
Ans: b
38. In a cable the voltage stress is maximum at
(a) sheath
(6) insulator
(e) surface of the conductor
(d) core of the conductor
Ans: d
39. Capacitance grading of cable implies
(a) use of dielectrics of different permeabilities
(b) grading according to capacitance of cables per km length
(c) cables using single dielectric in different concentrations
(d) capacitance required to be introduced at different lengths to counter the effect
of inductance
(e) none of the above
Ans: a
40. Underground cables are laid at sufficient depth
(a) to minimise temperature stresses
(b) to avoid being unearthed easily due to removal of soil
(c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc.
(d) for all of the above reasons
Ans: c
41. The advantage of cables over overhead transmission lines is
(a) easy maintenance
(b) low cost
(c) can be used in congested areas
(d) can be used in high voltage circuits
Ans: c
42. The thickness of metallic shielding on cables is usually
(a) 0.04 mm
(b) 0.2 to 0.4 mm
(e) 3 to 5 mm
(d) 40 to 60 mm
Ans: a
43. Cables for 220 kV lines are invariably
(a) mica insulated
(b) paper insulated
(c) compressed oil or compressed gas insulated
(d) rubber insulated
(e) none of the above
Ans: c
44. Is a cable is to be designed for use on 1000 kV, which insulation would you
prefer ?
(a) Polyvinyle chloride
(b) Vulcanised rubber
(c) Impregnated paper
(d) Compressed SFe gas
(e) none of the above
Ans: d
45. If a power cable and a communication cable are to run parallel the minimum
distance between the two, to avoid interference, should be
(a) 2 cm
(b) 10 cm
(c) 50 cm
(d) 400 cm
Ans: c
46. Copper as conductor for cables is used as
(a) annealed
(b) hardened and tempered
(c) hard drawn
(d) alloy with chromium
Ans: a
47. The insulating material should have
(a) low permittivity
(b) high resistivity
(c) high dielectric strength
(d) all of the above
Ans: d
48. The advantage of oil filled cables is
(a) more perfect impregnation
(b) smaller overall size
(c) no ionisation, oxidation and formation of voids
(d
(c) becomes double
(d) remains unchanged
Ans: c
29. In cables the charging current
(a) lags the voltage by 90°
(b) leads the voltage by 90°
(c) lags the voltage by 180°
(d) leads the voltage by 180° Ans: b
30. A certain cable has an insulation of relative permittivity 4. If the insulation is
replaced by one of relative permittivity 2, the capacitance of the cable will become
(a) one half
(6) double
(c) four times
(d) none of the above
Ans: a
31. If a cable of homogeneous insulation has a maximum stress of 10 kV/mm,
then the dielectric strength of insulation should be
(a) 5 kV/mm
(b) 10 kV/mm
(a) 15 kV/mm
(d) 30 kV/mm
Ans: b
32. In the cables, sheaths are used to
(a) prevent the moisture from entering the cable
(b) provide enough strength
(e) provide proper insulation
(d) none of the above
Ans: a
33. The intersheaths in the cables are used to
(a) minimize the stress
(b) avoid the requirement of good insulation
(c) provide proper stress distribution
(d) none of the above
Ans: c
34. The electrostatic stress in underground cables is
(a) same at the conductor and the sheath
(b) minimum at the conductor and maximum at the sheath
(c) maximum at the conductor and minimum at the sheath
(d) zero at the conductor as well as on the sheath
(e) none of the above
Ans: c
35. The breakdown of insulation of the cable can be avoided economically by the
use of
(a) inter-sheaths
(b) insulating materials with different dielectric constants
(c) both (a) and (b)
(d) none of the above
Ans: c
36. The insulation of the cable decreases with
(a) the increase in length of the insulation
(b) the decrease in the length of the insulation
(c) either (a) or (b)
(d) none of the above
Ans: a
37. A cable carrying alternating current has
(a) hysteresis losses only
(b) hysteresis and leakage losses only
(c) hysteresis, leakage and copper losses only
(d) hysteresis, leakage, copper and friction losses
Ans: b
38. In a cable the voltage stress is maximum at
(a) sheath
(6) insulator
(e) surface of the conductor
(d) core of the conductor
Ans: d
39. Capacitance grading of cable implies
(a) use of dielectrics of different permeabilities
(b) grading according to capacitance of cables per km length
(c) cables using single dielectric in different concentrations
(d) capacitance required to be introduced at different lengths to counter the effect
of inductance
(e) none of the above
Ans: a
40. Underground cables are laid at sufficient depth
(a) to minimise temperature stresses
(b) to avoid being unearthed easily due to removal of soil
(c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc.
(d) for all of the above reasons
Ans: c
41. The advantage of cables over overhead transmission lines is
(a) easy maintenance
(b) low cost
(c) can be used in congested areas
(d) can be used in high voltage circuits
Ans: c
42. The thickness of metallic shielding on cables is usually
(a) 0.04 mm
(b) 0.2 to 0.4 mm
(e) 3 to 5 mm
(d) 40 to 60 mm
Ans: a
43. Cables for 220 kV lines are invariably
(a) mica insulated
(b) paper insulated
(c) compressed oil or compressed gas insulated
(d) rubber insulated
(e) none of the above
Ans: c
44. Is a cable is to be designed for use on 1000 kV, which insulation would you
prefer ?
(a) Polyvinyle chloride
(b) Vulcanised rubber
(c) Impregnated paper
(d) Compressed SFe gas
(e) none of the above
Ans: d
45. If a power cable and a communication cable are to run parallel the minimum
distance between the two, to avoid interference, should be
(a) 2 cm
(b) 10 cm
(c) 50 cm
(d) 400 cm
Ans: c
46. Copper as conductor for cables is used as
(a) annealed
(b) hardened and tempered
(c) hard drawn
(d) alloy with chromium
Ans: a
47. The insulating material should have
(a) low permittivity
(b) high resistivity
(c) high dielectric strength
(d) all of the above
Ans: d
48. The advantage of oil filled cables is
(a) more perfect impregnation
(b) smaller overall size
(c) no ionisation, oxidation and formation of voids
(d
) all of the above
Ans: d
49. The disadvantage with paper as insulating material is
(a) it is hygroscopic
(6) it has high capacitance
(c) it is an organic material
(d) none of the above
Ans: a
50. The breakdown voltage of a cable depends on
(a) presence of moisture
(b) working temperature
(c) time of application of the voltage
(d) all of the above
Ans: d
51. It is difficult to maintain oil filled cables.
(a) Yes
(b) No
Ans: a
51. In capacitance grading a homogeneous dielectric is used.
(a) Yes
(b) No
Ans: b
52. In congested areas where excavation is expensive and inconvenient ‘draw in
system’ of laying of underground cables
is often adopted.
(a) Yes
(b) No
Ans: a
53. Natural rubber is obtained from milky sap of tropical trees.
(a) Yes
(b) No
Ans: a
54. Rubber is most commonly used insulation in cables.
(a) Yes
(b) No
Ans: a
59. Polyethylene has very poor dielectric and ageing properties.
(a) Yes
(b) No
Ans: b
60. The metallic sheath may be made of lead or lead alloy or of aluminium.
(a) Yes
(b) No
Ans: b
Ans: d
49. The disadvantage with paper as insulating material is
(a) it is hygroscopic
(6) it has high capacitance
(c) it is an organic material
(d) none of the above
Ans: a
50. The breakdown voltage of a cable depends on
(a) presence of moisture
(b) working temperature
(c) time of application of the voltage
(d) all of the above
Ans: d
51. It is difficult to maintain oil filled cables.
(a) Yes
(b) No
Ans: a
51. In capacitance grading a homogeneous dielectric is used.
(a) Yes
(b) No
Ans: b
52. In congested areas where excavation is expensive and inconvenient ‘draw in
system’ of laying of underground cables
is often adopted.
(a) Yes
(b) No
Ans: a
53. Natural rubber is obtained from milky sap of tropical trees.
(a) Yes
(b) No
Ans: a
54. Rubber is most commonly used insulation in cables.
(a) Yes
(b) No
Ans: a
59. Polyethylene has very poor dielectric and ageing properties.
(a) Yes
(b) No
Ans: b
60. The metallic sheath may be made of lead or lead alloy or of aluminium.
(a) Yes
(b) No
Ans: b
TRANSISTOR BIASING ➡️➡️➡️
1. Transistor biasing represents ……………. conditions
1. a.c.
2. d.c.
3. both a.c. and d.c.
4. none of the above
Ans : 2
2. Transistor biasing is done to keep ………… in the circuit
Proper direct current
Proper alternating current
The base current small
Collector current small
Ans : 1
3. Operating point represents ………….. Values of IC and VCE when signal is applied
The magnitude of signal
Zero signal values of IC and VCE
None of the above
Ans : 3
TRANSISTOR BIASING Questions and Answers pdf
4. If biasing is not done in an amplifier circuit, it results in ……………
Decrease in the base current
Unfaithful amplification
Excessive collector bias
None of the above
Ans : 2
5. Transistor biasing is generally provided by a ……………. Biasing circuit
Bias battery
Diode
None of the above
Ans : 1
6. For faithful amplification by a transistor circuit, the value of VBE
should ………. for a silicon transistor
Be zero
Be 0.01 V
Not fall below 0.7 V
Be between 0 V and 0.1 V
Ans : 3
7. For proper operation of the transistor, its collector should
have …………
Proper forward bias
Proper reverse bias
Very small size
None of the above
Ans : 2
8. For faithful amplification by a transistor circuit, the value of VCE
should ……….. for silicon transistor
Not fall below 1 V
Be zero
Be 0.2 V
None of the above
Ans : 1
9. The circuit that provides the best stabilization of operating point
is …………
Base resistor bias
Collector feedback bias
Potential divider bias
None of the above
Ans : 3
10. The point of intersection of d.c. and a.c. load lines
represents ………….. Operating point
Current gain
Voltage gain
None of the above
Ans : 1
11. An ideal value of stability factor is ………….. 100
200
More than 200
1
Ans : 4
12. The zero signal IC is generally ……………… mA in the initial stages
of a transistor amplifier
4
1
3
More than 10
Ans : 2
13. If the maximum collector current due to signal alone is 3 mA, then
zero signal collector current should be at least equal to ……….. 6 mA
mA
3 mA
1 mA
Ans : 3
14. The disadvantage of base resistor method of transistor biasing is
that it …………
Is complicated
Is sensitive to changes in ß
Provides high stability
None of the above
Ans : 2
15. The biasing circuit has a stability factor of 50. If due to
temperature change, ICBO changes by 1 µA, then IC will change
by …………
100 µA
25 µA
20 µA
50 µA
Ans : 4
16. For good stabilsation in voltage divider bias, the current I1 flowing
through R1 and R2 should be equal to or greater than
10 IB
3 IB
2 IB
4 IB
Ans : 1
17. The leakage current in a silicon transistor is about ………… the
leakage current in a germanium transistor
One hundredth
One tenth
One thousandth
One millionth
Ans : 3
18. The operating point is also called the …………. Cut off point
Quiescent point
Saturation point
None of the above
Ans : 2
19. For proper amplification by a transistor circuit, the operating
point should be located at the ………….. of the d.c. load line
The end point
Middle
The maximum current point
None of the above
Ans : 2
20. The operating point ………………… on the a.c. load line
Also line
Does not lie
May or may not lie
Data insufficient
Ans : 1
21. The disadvantage of voltage divider bias is that it has …………. High stability factor
Low base current
Many resistors
None of the above
Ans : 3
22. Thermal runaway occurs when ………. Collector is reverse biased
Transistor is not biased
Emitter is forward biased
Junction capacitance is high
Ans : 2
23. The purpose of resistance in the emitter circuit of a transistor
amplifier is to …………. Limit the maximum emitter current
Provide base-emitter bias
Limit the change in emitter current
None of the above
Ans : 3
24. In a transistor amplifier circuit VCE = VCB + …………….. VBE
2VBE
5 VBE
None of the above
Ans : 1
25. The base resistor method is generally used in ………
Amplifier circuits
Switching circuits
Rectifier circuits
None of the above
Ans : 2
26. For germanium transistor amplifier, VCE should ………….. for
faithful amplification
1. Transistor biasing represents ……………. conditions
1. a.c.
2. d.c.
3. both a.c. and d.c.
4. none of the above
Ans : 2
2. Transistor biasing is done to keep ………… in the circuit
Proper direct current
Proper alternating current
The base current small
Collector current small
Ans : 1
3. Operating point represents ………….. Values of IC and VCE when signal is applied
The magnitude of signal
Zero signal values of IC and VCE
None of the above
Ans : 3
TRANSISTOR BIASING Questions and Answers pdf
4. If biasing is not done in an amplifier circuit, it results in ……………
Decrease in the base current
Unfaithful amplification
Excessive collector bias
None of the above
Ans : 2
5. Transistor biasing is generally provided by a ……………. Biasing circuit
Bias battery
Diode
None of the above
Ans : 1
6. For faithful amplification by a transistor circuit, the value of VBE
should ………. for a silicon transistor
Be zero
Be 0.01 V
Not fall below 0.7 V
Be between 0 V and 0.1 V
Ans : 3
7. For proper operation of the transistor, its collector should
have …………
Proper forward bias
Proper reverse bias
Very small size
None of the above
Ans : 2
8. For faithful amplification by a transistor circuit, the value of VCE
should ……….. for silicon transistor
Not fall below 1 V
Be zero
Be 0.2 V
None of the above
Ans : 1
9. The circuit that provides the best stabilization of operating point
is …………
Base resistor bias
Collector feedback bias
Potential divider bias
None of the above
Ans : 3
10. The point of intersection of d.c. and a.c. load lines
represents ………….. Operating point
Current gain
Voltage gain
None of the above
Ans : 1
11. An ideal value of stability factor is ………….. 100
200
More than 200
1
Ans : 4
12. The zero signal IC is generally ……………… mA in the initial stages
of a transistor amplifier
4
1
3
More than 10
Ans : 2
13. If the maximum collector current due to signal alone is 3 mA, then
zero signal collector current should be at least equal to ……….. 6 mA
mA
3 mA
1 mA
Ans : 3
14. The disadvantage of base resistor method of transistor biasing is
that it …………
Is complicated
Is sensitive to changes in ß
Provides high stability
None of the above
Ans : 2
15. The biasing circuit has a stability factor of 50. If due to
temperature change, ICBO changes by 1 µA, then IC will change
by …………
100 µA
25 µA
20 µA
50 µA
Ans : 4
16. For good stabilsation in voltage divider bias, the current I1 flowing
through R1 and R2 should be equal to or greater than
10 IB
3 IB
2 IB
4 IB
Ans : 1
17. The leakage current in a silicon transistor is about ………… the
leakage current in a germanium transistor
One hundredth
One tenth
One thousandth
One millionth
Ans : 3
18. The operating point is also called the …………. Cut off point
Quiescent point
Saturation point
None of the above
Ans : 2
19. For proper amplification by a transistor circuit, the operating
point should be located at the ………….. of the d.c. load line
The end point
Middle
The maximum current point
None of the above
Ans : 2
20. The operating point ………………… on the a.c. load line
Also line
Does not lie
May or may not lie
Data insufficient
Ans : 1
21. The disadvantage of voltage divider bias is that it has …………. High stability factor
Low base current
Many resistors
None of the above
Ans : 3
22. Thermal runaway occurs when ………. Collector is reverse biased
Transistor is not biased
Emitter is forward biased
Junction capacitance is high
Ans : 2
23. The purpose of resistance in the emitter circuit of a transistor
amplifier is to …………. Limit the maximum emitter current
Provide base-emitter bias
Limit the change in emitter current
None of the above
Ans : 3
24. In a transistor amplifier circuit VCE = VCB + …………….. VBE
2VBE
5 VBE
None of the above
Ans : 1
25. The base resistor method is generally used in ………
Amplifier circuits
Switching circuits
Rectifier circuits
None of the above
Ans : 2
26. For germanium transistor amplifier, VCE should ………….. for
faithful amplification
:
Some basic facts an Electrical Engineer should know..! ➡️➡️
1. You need to know Ohm's law V=IR, current is proportional to the voltage applied.
2. Electric shock is caused by current and not voltage. 30mA of current is enough to cause ventricular fibrillation in your heart.
3. Megger is the name of a company. (Many people term measuring of Insulation resistance as Megger)
4. 'Exd' type equipments (sometimes called explosion proof) do not prevent explosion. They just help to isolate an explosion in the interior of the equipment from spreading outside.
5. Test before Touch. This is a mantra that every electrical engineer should remember. You need to check that there is no voltage before touching any live part. It may have been fed from a different source.
6. Nowadays, domestic fan regulators do not work on potential divider concept and there is no power loss if you operate the fan at lower/higher speeds.
7. System earthing and body earthing are different.
8. All motors are treated in kW/MW, transformers in MVA/kVA and fuses in A.
9. 'k' in kW, kVA, kA, kV need to be in smaller case and not as in KW, KVA, KA, KV.
10. Incidents can happen anytime and one should wear appropriate safety gear before working on an electrical installation.
11. In electrical cables, size of the core determines the amount of current it can carry and the thickness of Insulation determines the voltage level it can work at.
12. Making capacity of a circuit breaker is approximately 2.5 times its breaking capacity.
13. In transformers, Dyn11 vector group will become Yd1 if you change its primary and secondary sides.
14. Neutral is solidly grounded in the 415V system at the user end to protect people from shock.
15. 230V, that we measure is the rms value and the actual peak AC voltage is √2 * 230V.
16. Every electrical engineer should know how to give basic first aid and CPR. CPR can bring a dead person to life.
17. Zero watt bulbs available in the market are not actually rated for zero watt. Their ratings vary from 5W to 20W.
Some basic facts an Electrical Engineer should know..! ➡️➡️
1. You need to know Ohm's law V=IR, current is proportional to the voltage applied.
2. Electric shock is caused by current and not voltage. 30mA of current is enough to cause ventricular fibrillation in your heart.
3. Megger is the name of a company. (Many people term measuring of Insulation resistance as Megger)
4. 'Exd' type equipments (sometimes called explosion proof) do not prevent explosion. They just help to isolate an explosion in the interior of the equipment from spreading outside.
5. Test before Touch. This is a mantra that every electrical engineer should remember. You need to check that there is no voltage before touching any live part. It may have been fed from a different source.
6. Nowadays, domestic fan regulators do not work on potential divider concept and there is no power loss if you operate the fan at lower/higher speeds.
7. System earthing and body earthing are different.
8. All motors are treated in kW/MW, transformers in MVA/kVA and fuses in A.
9. 'k' in kW, kVA, kA, kV need to be in smaller case and not as in KW, KVA, KA, KV.
10. Incidents can happen anytime and one should wear appropriate safety gear before working on an electrical installation.
11. In electrical cables, size of the core determines the amount of current it can carry and the thickness of Insulation determines the voltage level it can work at.
12. Making capacity of a circuit breaker is approximately 2.5 times its breaking capacity.
13. In transformers, Dyn11 vector group will become Yd1 if you change its primary and secondary sides.
14. Neutral is solidly grounded in the 415V system at the user end to protect people from shock.
15. 230V, that we measure is the rms value and the actual peak AC voltage is √2 * 230V.
16. Every electrical engineer should know how to give basic first aid and CPR. CPR can bring a dead person to life.
17. Zero watt bulbs available in the market are not actually rated for zero watt. Their ratings vary from 5W to 20W.
Be zero
Be 0.2 V
Not fall below 0.7 V
None of the above
Ans : 3
27. In a base resistor method, if the value of ß changes by 50, then
collector current will change by a factor ………
25
50
100
200
Ans : 2
28. The stability factor of a collector feedback bias circuit is ……….. that of base resistor bias.
The same as
More than
Less than
None of the above
Ans : 3
29. In the design of a biasing circuit, the value of collector load RC is
determined by …………
VCE consideration
VBE consideration
IB consideration
None of the above
Ans : 1
30. If the value of collector current IC increases, then the value of
VCE …………
Remains the same
Decreases
Increases
None of the above
Ans : 2
31. If the temperature increases, the value of VCE …………
Remains the same
Is increased
Is decreased
None of the above
Ans : 3
32. The stabilisation of operating point in potential divider method is
provided by ………. RE consideration
RC consideration
VCC consideration
None of the above
Answer: 1
33. The value of VBE ……………. Depends upon IC to moderate extent
Is almost independent of IC
Is strongly dependant on IC
None of the above
Ans : 2
34. When the temperature changes, the operating point is shifted due
to ……. Change in ICBO
Change in VCC
Change in the values of circuit resistance
None of the above
Ans : 1
35. The value of stability factor for a base resistor bias is …………
RB (ß+1)
(ß+1)RC
(ß+1)
1-ß
Ans : 3
36. In a particular biasing circuit, the value of RE is about ………
10 kO
1 MO
100 kO
800 O
Ans : 4
37. A silicon transistor is biased with base resistor method. If ß=100,
VBE =0.7 V, zero signal collector current IC = 1 mA and VCC = 6V , what is the value of the base resistor RB?
105 kO
530 kO
315 kO
None of the above
Ans : 2
38. In voltage divider bias, VCC = 25 V; R1 = 10 kO; R2 = 2.2 V ; RC =
3.6 V and RE =1 kO. What is the emitter voltage?
7 V
3 V
V
8 V
Ans : 4
39. In the above question (Q38.) , what is the collector voltage?
3 V
8 V
6 V
7 V
Ans : 1
40. In voltage divider bias, operating point is 3 V, 2 mA. If VCC = 9 V,
RC = 2.2 kO, what is the value of RE ?
2000 O
1400 O
800 O
1600 O
Ans : 3
Be 0.2 V
Not fall below 0.7 V
None of the above
Ans : 3
27. In a base resistor method, if the value of ß changes by 50, then
collector current will change by a factor ………
25
50
100
200
Ans : 2
28. The stability factor of a collector feedback bias circuit is ……….. that of base resistor bias.
The same as
More than
Less than
None of the above
Ans : 3
29. In the design of a biasing circuit, the value of collector load RC is
determined by …………
VCE consideration
VBE consideration
IB consideration
None of the above
Ans : 1
30. If the value of collector current IC increases, then the value of
VCE …………
Remains the same
Decreases
Increases
None of the above
Ans : 2
31. If the temperature increases, the value of VCE …………
Remains the same
Is increased
Is decreased
None of the above
Ans : 3
32. The stabilisation of operating point in potential divider method is
provided by ………. RE consideration
RC consideration
VCC consideration
None of the above
Answer: 1
33. The value of VBE ……………. Depends upon IC to moderate extent
Is almost independent of IC
Is strongly dependant on IC
None of the above
Ans : 2
34. When the temperature changes, the operating point is shifted due
to ……. Change in ICBO
Change in VCC
Change in the values of circuit resistance
None of the above
Ans : 1
35. The value of stability factor for a base resistor bias is …………
RB (ß+1)
(ß+1)RC
(ß+1)
1-ß
Ans : 3
36. In a particular biasing circuit, the value of RE is about ………
10 kO
1 MO
100 kO
800 O
Ans : 4
37. A silicon transistor is biased with base resistor method. If ß=100,
VBE =0.7 V, zero signal collector current IC = 1 mA and VCC = 6V , what is the value of the base resistor RB?
105 kO
530 kO
315 kO
None of the above
Ans : 2
38. In voltage divider bias, VCC = 25 V; R1 = 10 kO; R2 = 2.2 V ; RC =
3.6 V and RE =1 kO. What is the emitter voltage?
7 V
3 V
V
8 V
Ans : 4
39. In the above question (Q38.) , what is the collector voltage?
3 V
8 V
6 V
7 V
Ans : 1
40. In voltage divider bias, operating point is 3 V, 2 mA. If VCC = 9 V,
RC = 2.2 kO, what is the value of RE ?
2000 O
1400 O
800 O
1600 O
Ans : 3