Multiple Choice Questions (MCQ) with Answers on DC Machines

Multiple Choice Questions (MCQ) with Answers on DC Machines

 

1-The following magnet is used in large machines to create magnetic flux

  1. Permanent magnet
  2. Electro magnet
  3. Temporary magnet
  4. Any of the above

(Ans: b)

 

2-The special device which converts AC into DC and vice versa is known as

  1. Armature
  2. Slip rings
  3. Split rings
  4. Field magnets

(Ans: c)

 

3-The following is (are) the part(s) of a field magnet.

  1. Yoke
  2. Pole cores
  3. Pole shoes
  4. All of the above

(Ans: d)

 

4-Function of _____ is to collect current from the commutator and supply it to the external load.

  1. Field magnet
  2. Armature
  3. Brushes
  4. Yoke

(Ans: c)

 

5-The brushes are ____ in shape.

  1. Triangular
  2. Rectangular
  3. Cylindrical
  4. Square

(Ans: b)

 

6-For larger machines

  1. Ball bearings are used at both driving and non driving ends.
  2. Ball bearings are used at driving end and roller bearings are used at non driving end.
  3. Roller bearings are used at driving end and ball bearings are used at non driving end.
  4.  Roller bearings are used at both driving and non driving ends.

(Ans: c)

 

7-The following is (are) keyed to the shaft

  1. Armature core
  2. Commutator
  3. Cooling fan
  4. All of the above

(Ans: d)

 

8-Which of the following generators have two field windings?

  1. Series wound generator
  2. Shunt wound generator
  3. Compound wound generator
  4. All of the above

(Ans: c)

 

9-A motor converts

  1. Mechanical energy into electrical energy
  2. Chemical energy into electrical energy
  3. Electrical energy into Mechanical energy
  4. Electrical energy into chemical energy

(Ans: c)

 

10-To produce dynamically induced emf, the following is (are) necessary

  1. A magnetic field
  2. A conductor
  3. Motion of conductor with respect to the field
  4. All of the above

(Ans: d)

 

 

11-Which of the following is also called ‘motor rule’?

  1. Fleming’s right hand rule
  2. Fleming’s left hand rule
  3. All of the above

(Ans: b)

 

12-Shaft torque equals to

  1. Net torque
  2. Friction torque
  3. Net torque + Friction torque + Torque lost
  4. Net torque – (Friction torque + Torque lost)

(Ans: d)

 

13-Iron or magnetic losses are also called

  1. Core losses
  2. Field losses
  3. Copper losses
  4. Armature losses

(Ans: a)

 

14-The mechanical losses are about _____ % of full load losses.

  1. 0 to 10
  2. 10 to 20
  3. 20 to 30
  4. 30 to 40

(Ans: b)