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A: When an electric motor is started, a ...

A: When an electric motor is started, a variable resistance (that decreases with time) is used in series. This resistance is known as motor slarter,
R: The back-emf in the beginning, when motor starts, is very small.

A

Both A and R are true and R is the correct explanation

B

Both A and R are true but R is not the correct explanation of A

C

A is true but R is false

D

Both A and R are false

Text Solution

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The correct Answer is:
A
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AAKASH SERIES-ELECTROMAGNETIC INDUCTION-EXERCISE-IB
  1. A : Total induced emf in a loop is not confined to any particular poin...

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  2. (A): Unlike electrostatic field the lines of induced field from closed...

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  3. A: The mutual Induction between the two coils infinitely apart is zero...

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  4. A: An inductor is called the inertia of an electric circuit. R: An ...

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  5. A: At any instant, if the current through an inductor is zero, then th...

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  6. A: There may be an induced emf in a loop without induced current. R:...

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  7. A: When the magnetic flux through a loop is maximum, induced emf is ma...

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  8. A: When a conducting loop is kept stationary in a non-uniform magnetic...

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  9. A: When an electric motor is started, a variable resistance (that decr...

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  10. A current I is flowing in a straight conductor of length L. The magnet...

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  11. A: Electrical power through transmission lines is transmitted at high ...

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  12. (A): The electric field induced due to changing magnetic field is non-...

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  13. (A): In equation F=q(E+v xx B) when v = 0, any force on the charge mus...

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  14. A: The induced current flows so as to oppose the cause producing it. ...

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  15. (A): Only a change in magnetic flux will maintain an induced current i...

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  16. (A): If changing current is flowing through a machine of iron eddy cur...

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  17. Assertion : The possibility of an electric bulb fusing is higher at t...

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  18. Assertion : An emf vec(E) is induced in a closed loop where magnetic f...

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