A 10 H inductor carries a current of 20 A. How much ice at 0°C could be melted by the energy stored in the magnetic field of the inductor?
Latent heat of ice is  2.26 × ${10}^3$ J/kg .

1.	0.08 kg	2.	8.8 kg
3.	0.88 kg	4.	0.44 kg

A copper rod of mass m slides under gravity on two smooth parallel rails l distance apart and set at an angle $\theta$ to the horizontal as shown in fig. At the bottom, the rails are joined by a resistance R. There is a uniform magnetic field perpendicular to the plane of the rails. The terminal velocity of the rod is:

1. $\frac{mgR\cos \theta }{B^2{l}^2}$

2. $\frac{mgR\sin \theta }{B^2{l}^2}$

3. $\frac{mgR\tan \theta }{B^2{l}^2}$

4. $\frac{mgR\mathrm{co}t\theta }{B^2{l}^2}$ 

Some magnetic flux is changed from a coil of resistance 10 $\mathrm{\Omega }$. As a result, an induced current is developed in it, which varies with time as shown in the figure. The magnitude of change in flux through the coil in Wb is:

In the circuit diagram shown in figure, R = 10 \(\Omega\), L = 5 H, E = 20 V and i = 2 A. This current is decreasing at a rate of 1.0 A/s. $V_{ab}$ at this instant will be:

A \(1~\text{m}\) long metallic rod is rotating with an angular frequency of \(400~\text{rad/s}\)$$ about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of \(0.5~\text{T}\) parallel to the axis exists everywhere. The emf induced between the center and the ring is:
1. \(200~\text{V}\)
2. \(100~\text{V}\)
3. \(50~\text{V}\)
4. \(150~\text{V}\)

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

The radius of a loop as shown in the figure is \(10~\mathrm {cm}.\) If the magnetic field is uniform and has a value \(10^{-2}~ T,\) then the flux through the loop will be:
 

If a current is passed through a circular loop of radius R then magnetic flux through a coplanar square loop of side l as shown in the figure (l<<R) is:

1. $\frac{{\mu }_{0}l}{2}\frac{R^2}{l}$

2. $\frac{{\mu }_{0}I{l}^2}{2R}$

3. $\frac{{\mu }_{0}l{\mathrm{\pi R}}^2}{2l}$

4. $\frac{{\mu }_0{\mathrm{\pi R}}^{2}I}{l}$

The magnetic flux linked with a coil varies with time as \(\phi = 2t^2-6t+5,\) where \(\phi \) is in Weber and \(t\) is in seconds. The induced current is zero at:
1. \(t=0\)
2. \(t= 1.5~\text{s}\)
3. \(t=3~\text{s}\)
4. \(t=5~\text{s}\)

Eddy currents are used in:

1. Induction furnace

2. Electromagnetic brakes

3. Speedometers

4. All of these