A horizontal straight wire 10 m long extending from east to west is falling with a speed of 5.0 ms^-1 at right angle to the horizontal component of the earth's magnetic field, \(0.30 \times 10^{-4} \mathrm{~Wb} \mathrm{~m}^{-2}\)$\mathrm{}$
. The instantaneous value of the emf induced in the wire is:

1.	\(2.5 \times 10^{-3} V\)
2.	\(1.5 \times 10^{-4} V\)
3.	\(2.5 \times 10^{-4} V\)
4.	\(1.5 \times 10^{-3} V\)

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Current in a circuit falls from \(5.0\) A to \(0\) A in \(0.1\) s. If an average emf of \(200\) V is induced, the self-inductance of the circuit is:
1. \(4\) H
2. \(2\) H
3. \(1\) H
4. \(3\) H

A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 to 20 A in 0.5 s, what is the change of flux linkage with the other coil?

1. 35 Wb

2. 25 Wb

3. 30 Wb

4. 20 Wb

In which of the following devices, the eddy current effect is not used?

1. Electric heater

2. Induction furnace

3. Magnetic braking in train

4. Electromagnet

What is the dimensional formula of magnetic flux?

1. $[\mathrm{M}$ ${\mathrm{L}}^2$ ${\mathrm{T}}^{-2}$ ${\mathrm{A}}^{-1}]$

2. $[\mathrm{M}$ ${\mathrm{L}}^1$ ${\mathrm{T}}^{-1}$ ${\mathrm{A}}^{-2}]$

3. $[\mathrm{M}$ ${\mathrm{L}}^2$ ${\mathrm{T}}^{-3}$ ${\mathrm{A}}^{-1}]$

4. $[\mathrm{M}$ ${\mathrm{L}}^{-2}$ ${\mathrm{T}}^{-2}$ ${\mathrm{A}}^{-2}]$

A cylindrical magnet is kept along the axis of a circular coil. On rotating the magnet about its axis, the coil will have induced in it:

The magnetic flux through a coil varies with time t as shown in the diagram. Which graph best represents the variation of the e.m.f. E induced in the coil with time t?

1.		2.
3.		4.

A bar magnet is made to fall through a long surface copper tube. The speed (v) of the magnet as a function of time (t) is best represented by:

When a conducting wire XY is moved towards the right, a current flows in the anti-clockwise direction. Direction of magnetic field at point O is:

Eddy currents are induced when:

1. A metal block is kept in a changing magnetic field.

2. A metal block is kept in a uniform magnetic field.

3. A coil is kept in a uniform magnetic field.

4. Current is passed in a coil.