Starting Electric Motors MCQ Questions & Answers

Starting Electric Motors MCQs : This section focuses on the "Starting Electric Motors". These Multiple Choice Questions (MCQs) should be practiced to improve the Starting Electric Motors skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

100 V, 2 A, 90 rpm separately excited dc motor with armature resistance (Ra) equal to 8 ohms. Calculate back emf developed in the motor when it operates on 3th/4 of the full load. (Assume rotational losses are neglected)

A. 100 V

B. 87 V

C. 88 V

D. 90 V

Question 2

A 10-pole, 3-phase, 60 Hz induction motor is operating at a speed of 100 rpm. The frequency of the rotor current of the motor in Hz is __________

A. 52.4

B. 54.8

C. 51.66

D. 51.77

Question 3

A 3-phase induction motor runs at almost 140 rpm at no load and 50 rpm at full load when supplied with power from a 50 Hz, 3-phase supply. What is the corresponding speed of the rotor field with respect to the rotor?

A. 20 revolution per minute

B. 80 revolution per minute

C. 90 revolution per minute

D. 70 revolution per minute

Question 4

Calculate the active power in a .45 H inductor.

A. 0.11 W

B. 0.14 W

C. 0.15 W

D. 0 W

Question 5

Calculate the active power in a .56 F capacitor.

A. 37.8 W

B. 0 W

C. 15.4 W

D. 124.5 W

Question 6

Calculate the active power in a .7889 H inductor.

A. .123 W

B. .155 W

C. 0 W

D. .487 W

Question 7

Calculate the active power in a .8 ? resistor with 2 A current flowing through it.

A. 2.4 W

B. 3.4 W

C. 2.2 W

D. 3.2 W

Question 8

Calculate the moment of inertia of the disc having a mass of 4 kg and diameter of 1458 cm.

A. 106.288 kgm2

B. 104.589 kgm2

C. 105.487 kgm2

D. 107.018 kgm2

Question 9

Calculate the moment of inertia of the thin spherical shell having a mass of 703 kg and diameter of 376 cm.

A. 1639.89 kgm2

B. 1628.47 kgm2

C. 1678.12 kgm2

D. 1978.19 kgm2

Question 10

Calculate the phase angle of the sinusoidal waveform z(t)=.99sin(4578?t+78?÷78).

A. ?÷3

B. 2?

C. ?÷7

D. ?

Question 11

Calculate the value of the torque when 1 N force is applied perpendicular to a 1 m length of chain fixed at the center.

A. 1 N-m

B. 3 N-m

C. 2 N-m

D. 4 N-m

Question 12

Calculate the value of the torque when 89 N force is applied perpendicular to a 78 m length of stick fixed at the center.

A. 6942 N-m

B. 3000 N-m

C. 1000 N-m

D. 4470 N-m

Question 13

The slope of the V-I curve is 16.8°. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.

A. .324 ?

B. .301 ?

C. .343 ?

D. .398 ?

Question 14

The unit of angular frequency is Hz.

A. True

B. False

Question 15

Calculate the active power in a .8 Ω resistor with 2 A current flowing through it.

A. 2.4 W

B. 3.4 W

C. 2.2 W

D. 3.2 W

Question 16

Calculate the phase angle of the sinusoidal waveform z(t)=.99sin(4578πt+78π÷78).

A. π÷3

B. 2π

C. π÷7

D. π

Question 17

The slope of the V-I curve is 16.8°. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.

A. .324 Ω

B. .301 Ω

C. .343 Ω

D. .398 Ω