﻿ Engineering Entrance Exam Question and Answers | Electromagnetic Induction - Zigya

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# Electromagnetic Induction

#### Multiple Choice Questions

1.

The self inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitance of

• 4µF

• 8µF

• 1µF

• 1µF

391 Views

2.

A boat is moving due east in a region where the earth's magnetic field is 5.0 × 10-5 NA-1m-1 due north and horizontal. The boat carries a vertical aerial 2m long. If the speed of the boat is 1.50 ms-1, the magnitude of the induced emf in the wire of aerial is

• 0.75 mV

• 0.50 mV

• 0.15 mV

• 0.15 mV

176 Views

3.

An inductor of inductance L = 400 mH and resistors of resistances R1 = 2 Ω and R2 = 2 Ω is connected to a battery of emf 12 V as shown in the figure. The internal resistance of the battery is negligible. The switch S is closed at t = 0. The potential drop across L as a function of time is • 6e–5t V

• • • 310 Views

4.

The flux linked with a coil at any instant ‘t’ is given by
φ= 10t2- 50t +250
The induced emf at t = 3 s is

• 190 V

• −190 V

• -10 V

• -10 V

377 Views

5.

A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earth’s magnetic field is 0.3 × 10−4 T, then the e.m.f. developed between the two ends of the conductor is

• depends on the nature of the metal used

• depends on the intensity of the radiation

• depends both on the intensity of the radiation and the metal used

• depends both on the intensity of the radiation and the metal used

218 Views

6.

Two identical conducting wires AOB and COD are placed at right angles to each other. The wire AOB carries an electric current I1 and COD carries a current I2. The magnetic field on a point lying at a distance ‘d’ from O, in a direction perpendicular to the plane of the wires AOB and COD, will be given by

• • • • 148 Views

7.

A coil having n turns and resistance 4R Ω. This combination is moved in time t seconds from a magnetic field W1 weber to W2 weber. The induced current in the circuit is

• • • • 150 Views

8.

Two concentric coils each of radius equal to 2π cm are placed at right angles to each other. 3 Ampere and 4 ampere are the currents flowing in each coil respectively. The magnetic induction in Weber/m2 at the centre of the coils will be (µ0 = 4π × 10−7 Wb/A-m)

• 12 × 10−5

• 10−5

• 5 × 10−5

• 5 × 10−5

350 Views

9.

A coil of inductance 300 mH and resistance 2Ω is connected to a source of voltage 2V. The current reaches half of its steady state value in

• 0.05 s

• 0.1 s

• 0.15 s

• 0.15 s

308 Views

10.

A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; it is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to

• development of air current when the plate is placed.

• induction of electrical charge on the plate

• shielding of magnetic lines of force as aluminium is a paramagnetic material.

• shielding of magnetic lines of force as aluminium is a paramagnetic material.

324 Views