EMF and Torque MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on EMF and Torque, a fundamental topic in the field of DC Machines. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our EMF and Torque MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of EMF and Torque mcq questions that explore various aspects of EMF and Torque problems. Each MCQ is crafted to challenge your understanding of EMF and Torque principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace DC Machines tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our EMF and Torque MCQs are your pathway to success in mastering this essential DC Machines topic.

Note: Each of the following question comes with multiple answer choices. Select the most appropriate option and test your understanding of EMF and Torque. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

So, are you ready to put your EMF and Torque knowledge to the test? Let's get started with our carefully curated MCQs!

EMF and Torque MCQs | Page 2 of 4

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Q11.
A 4-pole Dc wound machine is lap wound with 400 conductors. The pole shore is 20 cm long and average flux density over one-pole pitch is 0.4 T, the armature diameter being 30 cm. What is the value of flux/pole?

a.

0.188 Wb

b.

18.88 Wb

c.

0.0188 Wb

d.

1.888 Wb

Discuss
Answer: (c).0.0188 Wb
Q12.
A 4-pole Dc wound machine is lap wound with 400 conductors. The pole shore is 20 cm long and average flux density over one-pole pitch is 0.4 T, the armature diameter being 30 cm. What is the value of induced emf?

a.

188 V

b.

276 V

c.

94 V

d.

188 mV

Discuss
Answer: (a).188 V
Q13.
Coil torque for 20 kA armature current (T1) and 40 mA armature current (T2), will have ratio T1/T2=____ (assuming all other parameters same for both machines).

a.

1/2

b.

2/1

c.

1/4

d.

4/1

Discuss
Answer: (a).1/2
Q14.
If the no load speed of DC motor is 1300 rpm and full load speed is 1100 rpm, then its voltage regulation is ____________

a.

12.56 %

b.

18.18 %

c.

17.39 %

d.

18.39 %

Discuss
Answer: (b).18.18 %
Q15.
If the average coil emf of a DC motor is doubled and flux is halved (keeping other parameters constant) then its shaft speed will become ___________

a.

Twice of the original speed

b.

Square of the original speed

c.

Four times of the original speed

d.

Half of the original speed

Discuss
Answer: (c).Four times of the original speed
Q16.
A 4-pole wave wound DC motor drawing an armature current of 20 A has provided with 360 armature conductors. If the flux per pole is 0.015 Wb then the torque developed by the armature of motor is _______

a.

10.23 N-m

b.

34.37 N-m

c.

17.17 N-m

d.

19.08 N-m

Discuss
Answer: (b).34.37 N-m
Q17.
In a DC machine, what is the torque induced beyond the pole shoes?

a.

0

b.

2/π *∅*i

c.

π *∅*i/2

d.

Can’t be calculated

Discuss
Answer: (a).0
Q18.
For a constant emf, if field current is reduced then the speed of the DC motor will_____

a.

Remains same

b.

Increases

c.

Decreases

d.

Can’t say

Discuss
Answer: (b).Increases
Q19.
For an ideal DC machine, which phenomenon will reduce the terminal voltage?

a.

Armature reaction

b.

Commutation

c.

Armature ohmic losses

d.

All will contribute in reducing the terminal voltage

Discuss
Answer: (b).Commutation
Q20.
Product of torque and mechanical angular velocity ω is_____

a.

Ea/ω

b.

Ea*Ia

c.

ω/Ea

d.

Can’t tell

Discuss
Answer: (b).Ea*Ia
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