Quiz: Electrical Engineering

Exam: DFCCIL

Topic: AC fundamentals

Each question carries 1 mark.

Negative marking: 1/4 mark

Time: 10 Minute

Q1. A series circuit has R=4 Ω, X_L=12 Ω,X_C=9 Ω and is supplied with 200 V, 50 Hz. Calculate the power.

(a) 8000 W

(b) 19,200 W

(c) 6400 W

(d) 14,400 W

Q2. What is the peak value of the alternating voltage (in V) having an average value of 180 V?

(a) 254.59

(b) 282.57

(c) 333.34

(d) 359.96

Q3. What will be the instantaneous value of the alternating current, which is represented by i(t)=20 sin〖(13t-20)〗, when the value of t is 5?

(a) 10 A

(b) 0 A

(c) 17.32 A

(d) 14.14 A

Q4. A current wave is given by i = 4 + 2√2 sin 3θ + 4√2 sin 5θ. The r.m.s. value of current wave is ………

(a) 10 A

(b) 6 A

(c) √56 A

(d) 5 A

Q5. An alternating voltage is given by v = 100 sin 314 t volts. Its average value will be

………

(a) 70.7 V

(b) 50 V

(c) 63.7 V

(d) 100 V

Q6. The peak factor of a half-wave rectified a.c. is………

(a) 1.57

(b) 2

(c) 1.11

(d) 1.4142

Q7. A 40 Ω resistor is connected across a 15 V variable frequency source. The current

through the resistor when frequency is 100 Hz will be

(a) 0.5 A

(b) 0.1 A

(c) 0.375 A

(d) Cannot be found

Q8. In an a.c. circuit the instantaneous current and voltage are represented as

i= Im sin(ωt –π/6) and v = Vm sin (ωt + π/3).

The voltage leads the current by

(a) π/3

(b) π/2

(c) π/4

(d) π/6

Q9. In an RLC circuit, susceptance is equal to

(a) 1/R

(b) 1/X

(c) X/Z^2

(d) R/Z^2

Q10. The active and reactive power of an inductive circuit are 60 W and 80 VAR respectively. The power factor of the circuit is:

(a) 0.5 lag

(b) 0.6 lag

(c) 0.75 lag

(d) 0.8 lag

**SOLUTIONS**