R4RIN – MCQs, Mock Tests | IIT JEE IIT JEE Electromagnetic Induction Electromagnetic Waves Part 2

If in a galvanometer the coil is wound on a bad conductor the eddy current will be

1. zero
2. maximum
3. minimum
4. 50% of the actual value

✅ Correct Answer: 2

Eddy currents are also known as

1. Focault currents
2. Faraday currents
3. Huygen currents
4. Franklin currents

✅ Correct Answer: 1

Lenz s law gives the

1. magnitude of induced e. m. f.
2. magnitude of induced current
3. direction of current/emf induced
4. None of these

✅ Correct Answer: 3

If an e. m. f. of 300 micro volts is induced in a coil when current in it changes from 13 amperes to 7 amperes in 0.5 sec then the value of the self inductance of the coil will be25 micro henry20 micro henry27 micro henry

1. 25 micro henry
2. 20 micro henry
3. 27 micro henry
4. 17 micro henry

✅ Correct Answer: 1

A bar magnet falls through a metal ring. The acceleration will be

1. equal to g
2. less than g
3. greater than g
4. zero

✅ Correct Answer: 2

The laws of electromagnetic induction are the contribution of

1. Faraday
2. Maxwell
3. Lawrence
4. Hall

✅ Correct Answer: 1

L / R has the dimensions ofhenrytime

1. mass
2. length
3. henry
4. time

✅ Correct Answer: 4

The principle of eddy currents is used in

1. galvanometer
2. speedometer
3. pyrometer
4. barometer

✅ Correct Answer: 2

A transformer is used to light a 100W and 110 V lamp from a 230 V mains If the main current is 05 A the efficiency of the transformer is

1. 50%
2. 20%
3. 87%
4. 67%

✅ Correct Answer: 4

When power is drawn from the secondary coil of the transformer the dynamic resistance

1. remains same
2. decreases
3. increases
4. fluctuates.

✅ Correct Answer: 2

A 20V ac is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V the voltage across the coil is10 V8 V6 V

1. 16 V
2. 10 V
3. 8 V
4. 6 V

✅ Correct Answer: 1

An AC voltmeter reads 20 V across a resistor 30 V across an inductor and 15 V across a capacitor in LCR series circuit In this case the supply voltage will be

1. 100 V
2. 60 V
3. 50 V
4. 25 V

✅ Correct Answer: 4

The S.I. unit of magnitude flux is

1. Maxwell
2. Tesla
3. Weber
4. Henry

✅ Correct Answer: 3

The coil of a moving coil galvanometer is wound over metallic frames so that due to eddy currents the motion

1. remains the same
2. is damped
3. undamped
4. is made oscillatory

✅ Correct Answer: 2

Electromagnetic induction is the underlying phenomenon in the construction of

1. galvanometer
2. pyrometer
3. pyrometer
4. generator

✅ Correct Answer: 4

The property of an electric circuit by virtue of which any change in the magnetic flux linked with it induces an e m f in it is called

1. self-inductance
2. conductance
3. mutual induction
4. trans-conductance

✅ Correct Answer: 1

Lenzs law is a consequence of the law of conservation ofmassenergy

1. mass
2. energy
3. momentum
4. charge

✅ Correct Answer: 2

The frequency of ac in India is

1. 50 Hz
2. 50 kHz
3. 1420 MHz
4. 60 kHz

✅ Correct Answer: 1

The alternating voltage which we use in house has a peak value of nearly

1. 220 V
2. 280 V
3. 311 V
4. 300 V

✅ Correct Answer: 3

A step down transformer reduces 200 V to 110 V. The primary draws 5 amp. of current and secondary supplies 9 ampere. The efficiency of transformer is90%80%60%70%

1. 90%
2. 80%
3. 60%
4. 70%

✅ Correct Answer: 1