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
- Permanent magnet
- Electro magnet
- Temporary magnet
- Any of the above
(Ans: b)
2-The special device which converts AC into DC and vice versa is known as
- Armature
- Slip rings
- Split rings
- Field magnets
(Ans: c)
3-The following is (are) the part(s) of a field magnet.
- Yoke
- Pole cores
- Pole shoes
- All of the above
(Ans: d)
4-Function of _____ is to collect current from the commutator and supply it to the external load.
- Field magnet
- Armature
- Brushes
- Yoke
(Ans: c)
5-The brushes are ____ in shape.
- Triangular
- Rectangular
- Cylindrical
- Square
(Ans: b)
6-For larger machines
- Ball bearings are used at both driving and non driving ends.
- Ball bearings are used at driving end and roller bearings are used at non driving end.
- Roller bearings are used at driving end and ball bearings are used at non driving end.
- Roller bearings are used at both driving and non driving ends.
(Ans: c)
7-The following is (are) keyed to the shaft
- Armature core
- Commutator
- Cooling fan
- All of the above
(Ans: d)
8-Which of the following generators have two field windings?
- Series wound generator
- Shunt wound generator
- Compound wound generator
- All of the above
(Ans: c)
9-A motor converts
- Mechanical energy into electrical energy
- Chemical energy into electrical energy
- Electrical energy into Mechanical energy
- Electrical energy into chemical energy
(Ans: c)
10-To produce dynamically induced emf, the following is (are) necessary
- A magnetic field
- A conductor
- Motion of conductor with respect to the field
- All of the above
(Ans: d)
11-Which of the following is also called ‘motor rule’?
- Fleming’s right hand rule
- Fleming’s left hand rule
- All of the above
(Ans: b)
12-Shaft torque equals to
- Net torque
- Friction torque
- Net torque + Friction torque + Torque lost
- Net torque – (Friction torque + Torque lost)
(Ans: d)
13-Iron or magnetic losses are also called
- Core losses
- Field losses
- Copper losses
- Armature losses
(Ans: a)
14-The mechanical losses are about _____ % of full load losses.
- 0 to 10
- 10 to 20
- 20 to 30
- 30 to 40
(Ans: b)