Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 76

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IMPORTANT

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The output of a dynamo using a split ring commutator is

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Important Questions on Electromagnetic Induction and Alternating Currents

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IMPORTANT

Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 77

A dynamo dissipates

20 W

when it supplies a current of

4 A

through it. If the terminal potential difference is

220 V

, then, calculate the emf produced.

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IMPORTANT

Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 78

In the given circuit the peak voltages across $C, L$ and $R$ are $30 V, 110 V$ and $60 V$ respectively. The rms value of the applied voltage is

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Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 79

The frequency of an alternating current is

50 Hz

. What is the minimum time taken by current to reach its peak value from zero value?

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Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 80

An

A C

current is given by

I = I_{1} s i n ω t + I_{2} c o s ω t .

A hot wire ammeter will give a reading:

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Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 81

An

A C

source rated

220 V, 50 Hz

is connected to a resistor. The time taken by the current to change from its maximum to the rms value is :

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Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 82

An electric motor operating on a

50 V

DC supply draws a current of

12 A

. If the efficiency of the motor is

30 %

, estimate the resistance of the windings of the motor.

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Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 83

A step-up transformer operates on a

230 V

line and a load current of

2 A

. The ratio of primary and secondary windings is

1 : 25

. Then the current in the primary is:

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Physics Crash Course NEET>Chapter 15 - Electromagnetic Induction and Alternating Currents>Level 1>Q 84

For an

AC

given by

I = 50 \cos (100 t + 45 °) A

. The value of

I_{rms} =_________A

.