Quiz: Electrical Engineering

Exam: AE/JE

Topic: Miscellaneous

Each question carries 1 mark.

Negative marking: 1/4 mark

Time: 10 Minute

Q1. The current gain of a common emitter configuration of a transistor circuit is

(a) I_C/I_E

(b) I_E/C

(c) I_C/I_B

(d) I_B/I_C

Q2. A chopper circuit fed from an input voltage of 20 V DC, delivers a load power of 16 W. for a chopper efficiency of 0.8, the input current is

(a) 0.8 A

(b) 0.64 A

(c) 1 A

(d) 1.25 A

Q3. The Fourier series of a real periodic function has only

(P) cosine terms if it is even

(Q) sine terms if it is even

(R) cosine terms if it is odd

(S) sine terms if it is odd

Which of the above statements are correct?

(a) P and S

(b) P and R

(c) Q and S

(d) Q and R

Q4. If, in a DC machine, the ratio of constant losses to armature resistance is 3, then at maximum efficiency, the magnitude of current flowing will be:

(a) 3 A

(b) 1.732 A

(c) 9 A

(d) 6.667 A

Q5. A 6-pole DC machine having wave winding has………………number of parallel paths.

(a) 1

(b) 2

(c) 3

(d) 6

Q6. A GTO can be turned on by applying

(a) Positive gate signal

(b) Positive drain signal

(c) Positive source signal

(d) None of the above

Q7. A single-phase half wave rectifier is feeding a resistive load. When α = 0, dc output voltage is 127 V. When α = 30°, the dc output voltage will be about

(a) 127

(b) 119

(c) 110

(d) 100

Q8. Schering bridge is used to measure

(a) Dielectric loss

(b) The inductance

(c) Low resistance

(d) Mutual Inductance

Q9. An ac source is applied to pure inductive circuit. What is active power consumed by the circuit?

(a) Zero

(b) V^2/X_L

(c) VI

(d) 1/2 LI^2

Q10. An ammeter is obtained by shunting a 30 Ω resistance. What additional shunt should be connected across it to double the range?

(a) 5 Ω

(b) 10 Ω

(c) 15 Ω

(d) 30 Ω

**SOLUTIONS**

S8. Ans.(a)

Sol. Schering bridge is used to measure dielectric loss. It is an AC bridge circuit that is used for measuring the insulating properties of electrical cables and equipment. It has the advantage that the balance equation is independent of frequency.

Maxwell bridge is used to measure the value of unknown inductance.

Heaviside bridge is used to measured mutual inductance in terms of a known self-inductance.

Kelvin bridge is used to measure the value of low resistance.

S9. Ans.(a)

Sol. P=VI cos〖ϕ=VI cos〖90^0=0〗 〗(for pure inductor, ϕ=90

NOTE: pure inductor and capacitor consumes only reactive power.

S10. Ans.(d)

Sol. m=2=I/Im

∴Rsh=Rm/(m-1)=30/(2-1)=30 Ω