Quiz: Electrical Engineering 20 Jan 2021

Quiz: Electrical Engineering
Exam: NPCIL
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

Q1. Synchronous motor can operate at
(A) Lagging power factor only
(B) Leading power factor only
(C) Unity power factor only
(D) Lagging, leading and unity power factor only.

Q2 Standard frequency usually for electric supply is
(A) 50 Hz
(B) 60 Hz
(C) 50 to 60 Hz
(D) 50 to 55 Hz

Q3. In a steam locomotive the engine is
(A) Single cylinder
(B) Vertical
(C) Condensing
(D) Non-condensing

Q4. An unexcited single phase synchronous motor is
(A) reluctance motor
(B) repulsion motor
(C) universal motor
(D) AC series motor.

Q5. One kilowatt hour of electrical energy is the same as
(A) 36 × 10^5 watts
(B) 36 × 10^5 ergs
(C) 36 × 10^5 joules
(D) 36 × 10^5 B.T.U.

Q6. Low resistance can be accurately measured by
(A) Kelvin bridge
(B) Wheatstone bridge
(C) Wein’s bridge
(D) None of the above.

Q7. The maximum power developed in the synchronous motor will depend on
(A) rotor excitation only
(B) maximum value of coupling angle
(C) supply voltage only
(D) rotor excitation supply voltage and maximum value of coupling angle.

Q8. Resistivity of a wire depends on
(A) length
(B) material
(C) cross section area
(D) none of the above

Q9 In case the field of a synchronous motor is under excited, the power factor will be
(A) leading
(B) lagging
(C) zero
(D) unity.

Q10 The overall efficiency of a boiler in a thermal power plant is of the order of
(A)10%
(B) 25 to 30%
(C) 40 to 50%
(D) 70 to 80%

Solution

S1. Ans. (d)
Sol. Lagging, leading and unity power factor only.

S2. Ans. (a)
Sol. 50 Hz

S3. Ans. (d)
Sol. Non-condensing

S4. Ans. (a)
Sol. reluctance motor

S5. Ans. (c)
Sol. 36 × 10^5 Joules

S6. Ans. (a)
Sol. Kelvin bridge

S7. Ans. (d)
Sol. rotor excitation supply voltage and maximum value of coupling angle.

S8. Ans. (b)
Sol. Resistivity of a wire depends on material.

S9. Ans. (b)
Sol. lagging

S10. Ans. (d)
Sol. 70 to 80%

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