Circuits and Circuit Theory

41.In AC. circuits, laminated iron is invariably used in order to

  1. reduce eddy current loss
  2. increase heat radiation
  3. make assembly cheap and easier
  4. reduce circuit permeability

Correct answer: (A)
reduce eddy current loss

42.In an A.C. circuit power is dissipated in

  1. resistance only
  2. inductance only
  3. capacitance only
  4. none of the above

Correct answer: (A)
resistance only

43.In an AC. circuit, a low value of kVAR compared with kW indicates

  1. low efficiency
  2. high power factor
  3. unity power factor
  4. maximum load current

Correct answer: (B)
high power factor

44.In any A.C. circuit always

  1. apparent power is more than actual power
  2. reactive power is more than apparent power
  3. actual power is more than reactive power
  4. reactive power is more than actual power

Correct answer: (A)
apparent power is more than actual power

45.In each of the three coils of a three phase generator, an alternating voltage having an r.m.s. value of 220 V is induced. Which of the following values is indicated by the voltmeters?

  1. 220 V
  2. 220V3V
  3. 220/V3 V
  4. none of the above

Correct answer: (A)
220 V

46.In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of

  1. R only
  2. L only
  3. C only
  4. LorC

Correct answer: (D)
LorC

47.In series resonant circuit, increasing inductance to its twice value and reducing capacitance to its half value

  1. will change the maximum value of current at resonance
  2. will change the resonance frequency
  3. will change the impedance at resonance frequency
  4. will increase the selectivity of the circuit

Correct answer: (D)
will increase the selectivity of the circuit

48.In the case of an unsymmetrical alternating current the average value must always be taken over

  1. unsymmetrical part of the wave form
  2. the quarter cycle
  3. the half cycle
  4. the whole cycle

Correct answer: (D)
the whole cycle

49.Inductance affects the direct current flow

  1. only at the time of turning off
  2. only at the time of turning on
  3. at the time of turning on and off
  4. at all the time of operation

Correct answer: (C)
at the time of turning on and off

50.Inductance of coil

  1. is unaffected by the supply frequency
  2. decreases with the increase in supply frequency
  3. increases with the increase in supply frequency
  4. becomes zero with the increase in supply frequency

Correct answer: (C)
increases with the increase in supply frequency

Previous
Page 5 of 11
Next
Copyright © EngineeringMCQ.com