16 NOVEMBER 2021 CURRENT AFFAIRS QUIZ

In the dc motor the iron losses occur in

Field

Brushes

Armature

Commutator

TRUE ANSWER : ?
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By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?

Shaft

Commutator

Stator

Frame

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The speed of a dc motor can be controlled by changing

Armature circuit resistance

Is flux

All of the listed here

Aplied voltage

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In dc machines fractional pitch winding is used

To increase the generated emf

To reduce the sparking

To improve cooling

To reduce the generated emf

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If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens

This will make armature to take heavy current, possibly burning it

This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses

Motor will come to stop

Nothing will happen to motor

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The running speed of a dc series motor is basically determined by

Armature reaction

Field excitation

None of the listed here

Load

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Small dc motors up to 5 HP usually have

4 poles

6 poles

8 poles

2 poles

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In D.C. motor which of the following can sustain the maximum temperature rise?

Armature winding

Field winding

Commutator

Slip rings

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The commutating pole winding is connected in

None of the listed here

Series with the armature

Parallel with the armature

Series-parallel with the armature

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The dirction of rotation of a dc series motor can be changed by

Interchanging supply terminals

Interchanging field terminals

None of the listed here

Either of Interchanging field or Interchanging supply

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