Circuits and Circuit Theory

61.Pure inductive circuit takes power from the A.C. line when

1. applied voltage decreases but current increases
2. applied voltage increases but current decreases
3. both applied voltage and current increase
4. both applied voltage and current decrease

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62.Skin effect occurs when a conductor carries current at _________ frequencies.

1. very low
2. low
3. medium
4. high

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63.The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is

1. 4 kVAR
2. 6 kVAR
3. 8 kVAR
4. 16 kVAR

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64.The best place to install a capacitor is

1. very near to inductive load
2. across the terminals of the inductive load
3. far away from the inductive load
4. any where

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65.The double energy transient occur in the

1. purely inductive circuit
2. R-L circuit
3. R-C circuit
4. R-L-C circuit

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66.The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of

1. iron loss in core
2. skin effect
3. increase in temperature
4. capacitive effect between adjacent coil turns

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67.The equation of 50 Hz current sine wave having r.m.s. value of 60 A is

1. 60 sin 25 t
2. 60 sin 50 t
3. 84.84 sin 3141
4. 42.42 sin 314 t

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68.The form factor is the ratio of

1. peak value to r.m.s. value
2. r.m.s. value to average value
3. average value to r.m.s. value
4. none of the above

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69.The frequency of an alternating current is

1. the speed with which the alternator runs
2. the number of cycles generated in one minute
3. the number of waves passing through a point in one second
4. the number of electrons passing through a point in one second

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70.The frequency of domestic power supply in India is

1. 200 Hz
2. 100 Hz
3. 60 Hz
4. 50 Hz

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