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The back emf in a DC motor is maxi...

The back emf in a DC motor is maximum when,

A

the motor has picked up max speed

B

the motor has just started moving

C

the speed of motor is still on the increases

D

the motor has just been switched off

Text Solution

Verified by Experts

The correct Answer is:
A
The back e.m.f. in a motor is induced e.m.f., which is maximum, when speed of rotation the coil is maximum.
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DISHA PUBLICATION-ELECTROMAGNETIC INDUCTION -EXERCISE - 1 : Concept Builder
  1. Two circular coils can be arranged in any of the three situations show...

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  2. Two coils, one primary of 500 turns and one secondary of 25 turns, are...

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  3. Two circular coils, one of smaller radius r(1) and the other of very l...

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  4. A long solenoid has 500 turns. When a current of 2A is passed through ...

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  5. A metal disc of radius 100 cm is rotated at a constant angular speed o...

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  6. A copper disc of radius 0.1 m rotates about its centre with 10 revolut...

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  7. A square loop of side a is rotating about its diagonal with angular ve...

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  8. A wire loop is rotated in a uniform magnetic field about an an axis pe...

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  9. In an A.C. generator, when the plane of the armature is perpendicular ...

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  10. The pointer of a dead-beat galvanometer gives a steady deflection beca...

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  11. If a coil made of conducting wires is rotated between poles pieces of ...

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  12. The armature of a dc motor has 20 Omega resistance It draws a currrent...

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  13. When a metallic plate swings between the poles of a magnet

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  14. A generator has an e.m.f. of 440 Volt and internal resistance of 4000 ...

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  15. An AC generator of 220 V having internal resistance r=10 Omega and ext...

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  16. A six pole generotar with fixed field excitation developes an e.m.f. o...

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  17. The number of turns in the coil of an ac genrator is 5000 and the area...

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  18. plane of eddy currents make an angle with the plane of magnetic lines ...

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  19. The back emf in a DC motor is maximum when,

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  20. A series would dc motor has a total resistance of 1.5 ohm. When connec...

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