A.C circuit and networks. Part – 1

1. The r.m.s. Value of sinusoidal alternating current is given by the relation

A. IM/2

B. 0.637 IM

C. 2IM/π

D. IM/

2. The peak value of a sine wave is 100V its average value is –

A. 70.7 V

B. 141.4 V

C. 63.7 V

D. 100 V

3. Power factor of an ac circuit is defined as ratio of

A. Resistance and reactance

B. Resistance and impedance

C. Reactance and impedance

D. Reactance and resistance

4. In R-L-C series circuit the inductive reactance is 10Ω and the capacitive reactance is 15Ω. The total reactance is-

A. 25Ω

B. 5Ω

C. 1.5Ω

D. 18.03Ω

5. In a balanced 3 – phase, star connected system, the phase difference between phase voltages and their respective line voltages are –

A. 30⁰

B. 120⁰

C. 60⁰

D. 45⁰

6. Three identical resistances each of 15Ω are connected in star across a 400V, 3 phase supply. The value of resistance in each phase of the equivalent delta connected load would be

A. 5Ω

B. 45Ω

C. 30Ω

D. 7.5Ω

7. The relationship between the line and phase voltage of a delta connected circuit is given

A. V_L  = V_ph

B. V_L  =V_ph/

C. V_L  =  V_ph

D. V_L  =  V_ph/3

8. The time of complete one cycle of AC waveform is 0.25 second. The frequency of this waveform is:

A. 4 Hz

B. 40 Hz

C. 25 Hz

D. 2.5 Hz

9. the RMS value of a sinusoidal AC quantity is given by,

A. 1.41 V_max

B. V_max

C. 0.5 V_max

D. 0.707 V_max

10. Which of the following statements are correct in relation to AC circuits?

1. Sum of two AC currents each having RMS value 2A is 4A (RMS)

2. Sum of two AC currents each having RMS value 2A is less than 4A (RMS)

A. Both 1 and 2 are wrong

B. Both 1 and 2 are correct

C. Only 1 is correct

D. Only 2 is correct