## Network Theory MCQ Set 1

1. Resistance of a wire is yΩ. The wire is stretched to triple its length, then the resistance becomes

a) y/3

b) 3y

c) 6y

d) y/6

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2. An electric current of 10 A is the same as

a) 10 J/C

b) 10 V/C

c) 10C/sec

d) 10 W/sec

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3. Consider a circuit with two unequal resistances in parallel, then

a) large current flows in large resistor

b) current is same in both

c) potential difference across each is same

d) smaller resistance has smaller conductance

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4. In which of the following cases is Ohm’s law not applicable?

a) Electrolytes

b) Arc lamps

c) Insulators

d) Vacuum ratio values

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5. A copper wire of length l and diameter d has potential difference V applied at its two ends. The drift velocity is V. If the diameter of wire is made d/4, then drift velocity becomes

a) V/16

b) 16V

c) V

d) V/4

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6. Which of the following bulbs will have high resistance?

a) 220V, 60W

b) 220V,100W

c) 115V,60W

d) 115V,100 W

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7. Ohm’s law is not applicable to

a) dc circuits

b) high currents

c) small resistors

d) semi-conductors

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8. Conductance is expressed in terms of

a) mho

b) mho/m

c) ohm/m

d) m/ohm

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9. Resistivity of a wire depends on

a) length of wire

b) cross section area

c) material

d) all of the mentioned

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10. In a current-voltage relationship graph of a linear resistor, the slope of the graph will indicate

a) conductance

b) resistance

c) resistivity

d) a constant

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## Network Theory MCQ Set 2

1. Pick the incorrect statement among the following

a) Inductor is a passive element

b) Current source is an active element

c) Resistor is a passive element

d) Voltage source is a passive element

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2. For a voltage source to be neglected, the terminals across the source should be

a) replaced by inductor

b) short circuited

c) replaced by some resistance

d) open circuited

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3. Voltage source and terminal voltage can be related as

a) terminal voltage is higher than the source emf

b) terminal voltage is equal to the source emf

c) terminal voltage is always lower than source emf

d) terminal voltage cannot exceed source emf

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4. In case of ideal current sources, they have

a) zero internal resistance

b) low value of voltage

c) large value of currrent

d) infinite internal resistance

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5. In a network consisting of linear resistors and ideal voltage source, if the value of resistors are doubled, then voltage across each resistor

a) increases four times

b) remains unchanged

c) doubled

d) halved

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6. A practical current source can also be represented as

a) a resistance in parallel with an ideal voltage source

b) a resistance in parallel with an ideal current source

c) a resistance in series with an ideal current source

d) none of the mentioned

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7. A practical voltage source can also be represented as

a) a resistance in series with an ideal current source

b) a resistance in series with an ideal voltage source

c) a resistance in parallel with an ideal voltage source

d) none of the mentioned

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8. Constant voltage source is

a) active and bilateral

b) passive and bilateral

c) active and unilateral

d) passive and unilateral

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9. Which of the following is true about an ideal voltage source?

a) zero resistance

b) small emf

c) large emf

d) infinite resistance

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10. A dependent source

a) may be a current source or a voltage source

b) is always a voltage source

c) is always a current source

d) none of the mentioned

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11. With some initial change at t = 0+, a capacitor will act as

a) open circuit

b) short circuit

c) a current source

d) a voltage source

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12. If a current source is to be neglected, the terminals across the source are

a) replaced by a source resistance

b) open circuited

c) replaced by a capacitor

d) short circuited

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13. A constant current source supplies a electric current of 200 mA to a load of 2kΩ. When the load changed to 100Ω, the load current will be

a) 9mA

b) 4A

c) 700mA

d) 12A

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14. A voltage source having an open circuit voltage of 200 V and internal resistance of 50Ω is equivalent to a current source of

a) 4A with 50Ω in parallel

b) 4A with 50Ω in series

c) 0.5A with 50Ω in parallel

d) none of the mentioned

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15. A voltage source of 300 V has internal resistance of 4Ω and supplies a load having the same resistance. The power absorbed by the load is

a) 1150 W

b) 1250 W

c) 5625 W

d) 5000 W

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^{2}R.

## Network Theory MCQ Set 3

1. The direction of the cut-set is?

a) same as the direction of the branch current

b) opposite to the direction of the link current

c) same as the direction of the link current

d) opposite to the direction of the branch current

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2. Consider the graph shown below. The direction of the cut-set of node ‘a’ is?

a) right

b) left

c) upwards

d) downwards

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3. Consider the graph shown above in question 2. The direction of the cut-set at node ‘b’ will be?

a) upwards

b) right

c) downwards

d) left

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4. In the graph shown above in the question 2, the direction of the cut-set at node ‘c’ is?

a) downwards

b) upwards

c) left

d) right

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5. In the graph shown in the question 2, the direction of the cut-set at node ‘d’ will be?

a) left

b) downwards

c) right

d) upwards

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6. The row formed at node ‘a’ in the cut set matrix in the figure shown in question 2 is?

I_{1} I_{2} I_{3} I_{4} I_{5} I_{6} I_{7} I_{8}

a) +1 +1 +1 +1 0 0 0 0

b) +1 0 0 0 +1 0 0 +1

c) -1 0 0 0 -1 0 0 -1

d) -1 -1 0 0 -1 -1 0 0

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_{1}is same as cut set direction. So it is +1. Similarly for all other currents.

7. The row formed at node ‘c’ in the cut set matrix in the figure shown question 2 is?

a) -1 -1 0 0 +1 -1 0 0

b) 0 0 +1 0 0 -1 -1 0

c) +1 0 0 0 +1 0 0 +1

d) -1 0 0 0 -1 0 0 -1

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_{3}is same as cut set direction. So it is +1. Similarly for all other currents.

8. The number of cut set matrices formed from a graph is?

a) N^{N-1}

b) N^{N}

c) N^{N-2}

d) N^{N+1}

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^{N-2}cut set matrices.

9. For every tree there will be _____ number of cut set matrices.

a) 1

b) 2

c) 3

d) 4

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10. If a row of the cut set matrix formed by the branch currents of the graph is shown below. Then which of the following is true?

I_{1} I_{2} I_{3} I_{4} I_{5} I_{6} I_{7} I_{8}

-1 -1 0 0 +1 -1 0 0

a) -V_{1}-V_{2}+V_{5}-V_{6}=0

b) -I_{1}-I_{2}+I_{5}-I_{6}=0

c) -V_{1}+V_{2}+V_{5}-V_{6}=0

d) -I_{1}+I_{2}+I_{5}-I_{6}=0

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_{1}-I

_{2}+I

_{5}-I

_{6}=0.

## Network Theory MCQ Set 4

1. The highest power factor will be?

a) 1

b) 2

c) 3

d) 4

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2. If power factor = 1, then the current to the load is ______ with the voltage across it.

a) out of phase

b) in phase

c) 90⁰ out of phase

d) 45⁰ out of phase

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3. In case of resistive load, the power factor =?

a) 4

b) 3

c) 2

d) 1

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4. If power factor = 0, then the current to a load is ______ with the voltage.

a) in phase

b) out of phase

c) 45⁰ out of phase

d) 90⁰ out of phase

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5. For reactive load, the power factor is equal to?

a) 0

b) 1

c) 2

d) 3

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6. Average power is also called?

a) apparent power

b) reactive power

c) true power

d) instantaneous power

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7. If we apply a sinusoidal voltage to a circuit, the product of voltage and current is?

a) true power

b) apparent power

c) average power

d) reactive power

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8. The expression of apparent power (P_{app}) is?

a) V_{m}I_{m}

b) V_{m}I_{eff}

c) V_{eff}I_{eff}

d) V_{eff}I_{m}

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_{app}) is P

_{app}= V

_{eff}I

_{eff}.

9. The power factor=?

a) sinθ

b) cosθ

c) tanθ

d) secθ

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10. The power factor is the ratio of ________ power to the ______ power.

a) average, apparent

b) apparent, reactive

c) reactive, average

d) apparent, average

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11. The power factor is called leading power factor in case of ____ circuits.

a) LC

b) RC

c) RL

d) RLC

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12. The term lagging power factor is used in which circuits?

a) RLC

b) RC

c) RL

d) LC

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## Network Theory MCQ Set 5

1. Reciprocity Theorem is applied for _____ networks.

a) Linear

b) Bilateral

c) Linear bilateral

d) Lumped

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2. Reciprocity Theorem is used to find the change in _______ when the resistance is changed in the circuit.

a) Voltage

b) Voltage or current

c) Current

d) Power

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3. Find the current through 3Ω resistor in the circuit shown below.

a) 1

b) 2

c) 3

d) 4

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4. Determine the current flowing in the ammeter having 1Ω internal resistance connected in series with the 3Ω resistor shown in the circuit shown in the question 3.

a) 0.91

b) 0.92

c) 0.93

d) 0.94

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5. Find the current through 6Ω resistor in the circuit shown below.

a) 0.33

b) 0.44

c) 0.55

d) 0.66

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6. Determine the current flowing in the ammeter having 1Ω internal resistance connected in series with the 6Ω resistor shown in the circuit shown in the question 5.

a) 0.4

b) 0.45

c) 0.9

d) 0.95

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7. Find the current through 6Ω resistor in the circuit shown below.

a) 0.11

b) 0.22

c) 0.33

d) 0.44

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8. Determine the current flowing in the ammeter having 1Ω internal resistance in series with the 6Ω resistor shown in the circuit shown in the question 7.

a) 0.1

b) 0.2

c) 0.3

d) 0.4

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9. Find the current through 3Ω resistor in the circuit shown below.

a) 0.45

b) 0.56

c) 0.67

d) 0.78

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10. Determine the current flowing in the ammeter having 1Ω internal resistance in series with the 3Ω resistor shown in the circuit shown in the question 9.

a) 0.6

b) 0.7

c) 0.8

d) 0.9

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## Network Theory MCQ Set 6

1. The wattmeter method is used to measure power in a three-phase load. The wattmeter readings are 400W and -35W. Calculate the total active power.

a) 360

b) 365

c) 370

d) 375

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_{1}+ W

_{2}= 400 + (-35) =365W.

2. In the question 2 find the power factor.

a) 0.43

b) 0.53

c) 0.63

d) 0.73

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_{R}– W

_{Y})/(W

_{R}+ W

_{Y})) => tanØ = √3 (400-(-35))/(400+(-35) )=2.064 => Ø = 64.15⁰. Power factor = 0.43.

3. Find the reactive power in the question 2.

a) 751.44

b) 752.44

c) 753.44

d) 754.44

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_{L}I

_{L}sinØ. We know that W

_{R}– W

_{Y}= 400-(-35)) = 435 = V

_{L}I

_{L}sinØ. Reactive power = √3 x 435 = 753.44 VAR.

4. The input power to a three-phase load is 10kW at 0.8 Pf. Two watt meters are connected to measure the power. Find the reading of higher reading wattmeter.

a) 7.165

b) 6.165

c) 6.165

d) 4.165

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_{R}+ W

_{Y}= 10kW. Ø = cos

^{-1}0.8=36.8

^{o}=> tanØ = 0.75 = √3 (W

_{R}-W

_{Y})/(W

_{R}+W

_{Y})=(W

_{R}-W

_{Y})/10. W

_{R}-W

_{Y}=4.33kW. W

_{R}+W

_{Y}=10kW. W

_{R}=7.165kW.

5. Find the reading of higher reading wattmeter in the question 2.

a) 1.835

b) 2.835

c) 3.835

d) 4.835

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_{R}+ W

_{Y}= 10kW. Ø = cos

^{-1}0.8=36.8

^{o}=> tanØ = 0.75 = √3 (W

_{R}-W

_{Y})/(W

_{R}+W

_{Y})=(W

_{R}-W

_{Y})/10. W

_{R}-W

_{Y}=4.33kW. W

_{R}+W

_{Y}=10kW. W

_{Y}=2.835kW.

6. The readings of the two watt meters used to measure power in a capacitive load are -3000W and 8000W respectively. Calculate the input power. Assume RYB sequence.

a) 5

b) 50

c) 500

d) 5000

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_{R}+W

_{Y}= -3000+8000 = 5000W

7. Find the power factor in the question 6.

a) 0.25

b) 0.5

c) 0.75

d) 1

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_{R}=-3000. W

_{Y}=8000. tanØ = √3 (8000-(-3000))/5000=3.81 => Ø = 75.29⁰ => cosØ = 0.25.

8. The wattmeter reading while measuring the reactive power with wattmeter is?

a) V_{L}I_{L}secØ

b) V_{L}I_{L}sinØ

c) V_{L}I_{L}tanØ

d) V_{L}I_{L}cosØ

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_{L}I

_{L}sinØ VAR.

9. The total reactive power in the load while measuring the reactive power with wattmeter is?

a) √3V_{L}I_{L}cosØ

b) √3V_{L}I_{L}tanØ

c) √3V_{L}I_{L}sinØ

d)√3 V_{L}I_{L}secØ

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_{L}I

_{L}sinØ.

10. A single wattmeter is connected to measure reactive power of a three-phase, three-wire balanced load. The line current is 17A and line voltage is 440V. Calculate the power factor of the load if the reading of the wattmeter is 4488 VAR.

a) 0.6

b) 0.8

c) 1

d) 1.2

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_{L}I

_{L}sinØ => 4488 = 440 x 17sinØ => sinØ = 0.6. Power factor = cosØ = 0.8.

## Network Theory MCQ Set 7

1. The response of a second order system is?

a) pulse

b) saw tooth

c) square

d) sinusoid

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2. If a function f(t) is periodic, then?

a) f (t) = f(t+T)

b) f(t) = f(t+T/2)

c) f(t) = f(t+T/4)

d) f(t) = f(t+T/8)

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3. The period of a function is measured as?

a) zero crossing of one cycle to zero crossing of next cycle

b) positive peak of one cycle to positive peak of next cycle

c) negative peak of one cycle to negative peak of next cycle

d) all of the mentioned

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4. The number of cycles a wave completes in one second is called?

a) time period

b) frequency

c) energy

d) wavelength

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5. The relation between frequency and time period is?

a) f=1/T

b) f=T

c) f=1/T^{2}

d) f=1/T^{3}

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6. The period of a sine wave is 40ms. What is the frequency?

a) 25

b) 50

c) 75

d) 100

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7. The frequency of a sine wave is 30Hz. What is its period?

a) 3333ms

b) 333.3ms

c) 33.33ms

d) 3.333ms

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8. A sine wave completes half cycle in ____ radians.

a) π/2

b) π

c) π/4

d) 2π

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9. A sine wave completes quarter cycle in ____ radians.

a) 2π

b) π

c) π/2

d) π/4

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10. A sine wave completes full cycle in ____ radians.

a) π

b) 2π

c) π/4

d) π/2