Basic Electrical Engineering: Part-6 Objective Questions

Objective Questions From Basic Electrical Engineering:

[1] In ac circuit, the ratio of kW/kVA is
A. Power factor
B. Form factor
C. Load factor
D. Diversity factor

[2] Suppose that two ac waves have the same frequency but differ in phase by exactly 1/20 of a cycle. What is the phase difference between these two waves?

A. 18°

B. 20°

C. 36°

D. 5.73°

[3] The unit of inductance is

A. Mho
B. Hendry
C. Ohm
D. Farad

[4] What is the angular frequency of the ac signal having a frequency of 1770Hz

A. 1770 rad/s

B. 11,120 rad/s

C. 282 rad/s

D. Data insufficient

[5] Thevenin's equivalent circuit consists of

A. Series combination of R_th, E_th, Rl
B. Series combination of Rth, Eth
C. Parallel combination of Rth, Eth, Rl
D. Parallel combination of Rth, Eth

[6] The frequency of DC supply is
A. 16 2/3 Hz
B. 60 Hz
C. 50 Hz
D. 0 Hz

[7] Load factor is defined as the ratio of
A. Max demand/ Average demand
B. Average demand/ Connected load
C. Average demand/ Max. demand
D. Connected load/ Max demand

[8] Q factor of an inductive coil is given by

A. 2π fL/R
B. 2π f_r/R
C. R/Z
D. lr/l

[9] The rms value of sinusoidal 100V peak to peak is
A. 100 V
B. 50/√2 V
C. 50 V
D. 100/√2 V

[10] Which of the following bulbs will have the least resistance?

A. 220V, 60W
B. 220V, 100W
C. 115V, 60W
D. 115V, 100W

Solution Hint:
[2] One cycle = 360°.
1/20 of cycle is 360/20 = 18°

[4] Angular frequency ω = 2πf (rad/s)

[7] Some of the important terms in power system:
Demand factor = maximum demand / Connected load
Diversity factor = Sum of individual max. demands / Max. demand on power station
The ratio of average load to the maximum demand during a given period is known as load factor.
Load Factor = Average Load / maximum demand

[8] Quality factor is the ratio of reactive power to average power (Q/P)
Q_s = [I²X_L]/[I²R]
Q_s = X_L/R
Q_s = ωL/R
Q_s=2π fL/R

[9] V_rms = V_m/√2

Thanks for reading....