1.

The direction of induced current in the loop abc is:

(a) along abc if I decreases (b) along acb if I increases

(c) along abc if I is constant (d) along abc if I increases

2.

A bar magnet is dropped in a hollow metallic cylinder along its vertical axis. The acceleration of the falling magnet will be :

(a) zero (b) equal to g (c) less than g (d) greater than g

3.

Figure shows a rectangular conductor PSRQ in which movable arm PQ has a resistance ‘r’ and resistance of PSRQ is negligible. The magnitude of emf induced when PQ is moved with a velocity v does not depend on:

(a) magnetic field (b) velocity (c) resistance (r) (d) length of PQ

4.

A square shaped coil of side 10 cm, having 100 turns is placed perpendicular to a magnetic field which is increasing at 1 T/s. The induced emf in the coil is 

(a) 0.1 V (b) 0.5V (c) 0.75 V (d) 1.0V

5.

A circular coil of radius 8.0 cm and 40 turns is rotated about its vertical diameter with an angular speed of rad s–1  in a uniform horizontal magnetic field of magnitude 3.0 × 10–2 T. The maximum emf induced in the coil is :

(a) 0·12 V (b) 0·15 V (c) 0·19 V (d) 0·22 V

1.

A small flat search coil of area 5 cm2 with 140 closely wound turns is placed between the poles of a powerful magnet producing magnetic field 0·09 T and then quickly removed out of the field region. Calculate

(a) change of magnetic flux through the coil, and

(b) emf induced in the coil.

(CBSE 2019, 2M)

2.

(a) How are eddy currents generated in a conductor which is subjected to a magnetic field?

(b) Write two examples of their useful applications.

(c) How can the disadvantages of eddy currents be minimized?

(CBSE 2019, 3M)

3.

A rectangular conductor MNPQ with a movable arm MN (resistance r) is kept in a uniform magnetic field as shown in the figure. Resistance of arms MQ, QP and PN are negligible. Obtain the expression for the:

(a) current induced in the loop specifying its direction, and

(b) power required to move the arm.

(CBSE 2023, 3M)

4.

The figure shows a rectangular conducting frame MNOP of resistance R placed partly in a perpendicular magnetic fieldand moved with velocity as shown in the figure.

Obtain the expressions for the

(a) force acting on the arm ‘ON’ and its direction, and

(b) power required to move the frame to get a steady emf induced between the arms MN and PO.

(CBSE 2019, 3M)

5.

(a) Derive an expression for the induced emf developed when a coil of N turns, and area of cross-section A, is rotated at a constant angular speed ω  in a uniform magnetic field B.

(b) A wheel with 100 metallic spokes each 0·5 m long is rotated with a speed of 120 rev/min in a plane normal to the horizontal component of the Earth’s magnetic field. If the resultant magnetic field at that place is 4 × 10–4 T and the angle of dip at the place is 30˚, find the emf induced between the axle and the rim of the wheel.

(CBSE 2019, 5M)

Chapter Name

Sub Topics of Chapter 6: Electromagnetic Induction

Electromagnetic Induction

6.1 Introduction

6.2 Magnetic Flux

6.3 Faraday’s Laws of Electromagnetic Induction

6.4 Lenz’s Law

6.5 Motional Electromotive Force

6.6 Eddy Currents

6.7 Self-Inductance

6.8 Mutual Inductance

6.9 Energy Stored in a Magnetic Field

6.10 Transformers