Quiz: Electrical Engineering

Exam: UPSSSC JE

Topic: AC fundamentals

Each question carries 1 mark.

Negative marking: 1/4 mark

Time: 10 Minute

Q1. A Tank circuit consist of

(a) an inductor and a capacitor connected in series

(b) an inductor and a capacitor connected in parallel

(c) a pure inductor and a pure capacitor connected in series

(d) a pure inductor and a pure capacitor connected in parallel

Q2. In a series R-L-C circuit, “Q-factor” is given by

(a) Q= 1/R √(L/C)

(b) Q= R√(L/C)

(c) Q= 1/R √(C/L)

(d) Q= R√(C/L)

Q3. A non-sinusoidal periodic waveform is free from DC component, cosine components and even harmonics. The waveform has

(a) half wave and odd function symmetry

(b) half wave and even function symmetry

(c) only odd function symmetry

(d) only half wave symmetry

Q4. The main reason for using high voltage for long distance power transmission is

(a) reduction in transmission losses

(b) reduction in time of transmission

(c) increase in system reliability

(d) none of these

Q5. Capacitors used for improvement of power factor of a system

(a) Draws lagging power and supply leading power

(b) Draws lagging power and supply lagging power

(c) Draws leading power and supply lagging power

(d) Draws leading power and supply leading power

Q6. Materials having high dielectric constants, which is non-linear is called

(a) hard dielectrics

(b) super dielectrics

(c) Ferroelectric material

(d) paramagnetic material

Q7. For a sinusoidal waveform, the ratio of average value to rms value is

(a) π/(2√2)

(b) √2π/2

(c) 2/√2π

(d) (2√2)/π

Q8. The current in the circuit follows the relation i=200 sinωt. If frequency is 50 Hz, how long will it take for the current to rise to 100A?

(a) 2.89 ms

(b) 1.66 ms

(c) 6.84 ms

(d) 1.96 ms

Q9. The power of single-phase AC circuit is given by

(a) VI

(b) VI cos Ǿ

(c) VI sin Ǿ

(d) None of these

Q10. Which of the following distribution system is used for combined power and lighting load?

(a) single phase 2-wire AC system

(b) Three phase 3-wire AC system

(c) Three phase 4-wire AC system

(d) None of these

Solutions

S1. Ans. (d)

Sol. a pure inductor and a pure capacitor connected in parallel

S2. Ans. (a)

Sol. Q= 1/R √(L/C)

S3. Ans. (a)

Sol. half wave and odd function symmetry

S4. Ans. (a)

Sol. Reduction in transmission losses

S5. Ans. (c)

Sol. Draws leading power and supply lagging power

S6. Ans. (c)

Sol. Ferroelectric material

S7. Ans. (d)

Sol. (2√2)/π ; For sinusoidal waveform,I_av=I_m/(π/2)=〖2I〗_m/π

I_rms=I_m/√2

So, I_av/I_rms =(2√2)/π

S8. Ans. (b)

Sol. Given, i=200 sinωt

Time to reach 100 A. Putting i=100 A

100=200 sinωt

1/2=sinωt

ωt=π/6

t=1.66 ms

S9. Ans. (b)

Sol. VI cos Ǿ

S10. Ans. (c)

Sol. Three phase 4-wire AC system