31. The effect due to electric current are
a. Magnetic effect
b. Heating effect
c. Luminous effect

32. The rms value of the waveform shows in fig 14 will be
a. 73.3
b. 57.7
c. 43.7
d. 37.7

33. When ac flows through a resistance , then
a. current lead emf
b. current lags emf
c. current and emf are inphase
d. none of the above

34. The power factor of incandescent bulb is
a. 0.8 lagging
b. dc only
c. unity
d. zero

35. A incandescent bulb can work on
a. ac only
b. dc only
c. both ac as well as dc
d. depend on the shape of the coil

36. It is known that a given capacitor will fail if the terminal voltage exceeds 180 V. if the circuit is operating on sinusoidal steady voltage . the maximum rms voltage that may be applied to the capacitor will be
a. 150 N
b. 127 V
c. 97 V
d. 67 V

37. For an alternating voltage form factor is
a. RMS value / Mean value
b. Mean value / RMS value
c. RMS value / Peak value
d. Peak value / RMS value

38. Power factor of the magnetizing component of a transformer is
a. unity
b. 0.8 lagging
c. always leading
d. zero

39. Which of the following statement is not necessarily valid for ac currents
a. interference with communication lines
b. is suitable for charging batteries
c. developes eddy current losses
d. provides better safety as compared to direct current

40. A circuit has impedance of (3 + j4) . If a voltage (100 + j50) is applied , the power in the circuit will be
a. 100 W
b. 250 W
c. 500 W
d. 660 W