Complex AC MCQs

Question 1

Which of the following waves has the highest value of peak factor?

Accepted Answer

Half wave rectified sine wave

Answer

Square

Answer

Sine wa

Answer

Triangular wave

Question 2

The r.m.s. value of half wave rectified sine wave is 200 V. The r.m.s. value of full wave rectified A.C. will be

Accepted Answer

282.8 V

Answer

141.4 V

Answer

111V

Answer

100 V

Question 3

The voltagein a circuit follows the law v = 100 sin cot If the frequency is 25 Hz, how long will it take for the voltageto rise to 50 volts?

Accepted Answer

phase sequence can be easily changed

Answer

line current

Answer

two voltages can be used

Answer

it is a simple arrangement

Question 4

The negative maximum of a cosine wave occurs at

Accepted Answer

180?

Answer

30?

Answer

45?

Answer

90?

Question 5

Ina series R-L circuit the instantaneous voltage is given by (wL)2 ',sin (cot + tan-1 (1) The above equation indicates that

Accepted Answer

the current lags the voltage by ancoL angle tan R

Answer

the current leads the voltage by an_1 angle tan ?R

Answer

the current lags the voltage by 60?

Answer

the current leads the voltage by 60?

Question 6

Ohm is unit of all of the following except

Accepted Answer

Answer

inductive reactance capacitive reactance

Answer

resistance

Answer

capacitance

Question 7

If A = 8L30? and B = 2L15? the value of A/B will be

Accepted Answer

4Z15?

Answer

6L30?

Answer

8Z15?

Answer

none of the above

Question 8

The series and parallel resonance on L-C circuit differs in that

Accepted Answer

series resistance needs a low resistance source for sharp rise in current series

Answer

needs a lowresistance source for a sharp increase in impedance

Answer

resonance needs a high-resistance source for sharp increase in current parallel resonance

Answer

parallel resonance needs a lowresistance source for a sharp rise in line current

Question 9

Which of the following expression is true of apparent power in an A.C. circuit?

Accepted Answer

Vr m s x trm.s.

Answer

VI cos (1)

Answer

Vav x law,

Answer

Vpeak x Ipeak