In a uniform magnetic field, a ring is rotating about its axis which is parallel to the magnetic field and the magnetic field is perpendicular to the plane of the ring. The induced electric field in the ring:

1.	Is zero.
2.	Depends on the radius of the ring.
3.	Depends on the nature of the material of the ring.
4.	Depends on the product of the magnetic field and speed.

Calculate the self-inductance of a solenoid having \(1000\) turns and length \(1\) m. (The area of cross-section is \(7\) cm² and \(\mu_r=1000).\)

1. \(888\) H

2. \(0.88\) H

3. \(0.088\) H

4. \(88.8\) H

A rod having length \(l\) and resistance \(R_0\) is moving with speed \(v\) as shown in the figure. The current through the rod is:

1. \(\frac{B l v}{\frac{R_{1} R_{2}}{R_{1} + R_{2}} + R_{0}}\)

2. \(\frac{Blv}{\left(\frac{1}{R_{1}} + \frac{1}{R_{2}} + \frac{1}{R_{o}}\right)^{2}}\)

3. \(\frac{B l v}{R_{1} + R_{2} + R_{0}}\)

4. \(\frac{B l v}{\frac{1}{R_{1}} + \frac{1}{R_{2}} + \frac{1}{R_{0}}}\)

The slotting processes in a metallic sheet results in:

\(1 .\) \(\frac{E^{2}}{2 R}\)
\(2 .\) \(\frac{E^{2} L}{2 R^{2}}\)
\(3 .\) \(\frac{E^{2} L}{R}\) \(\)
\(4 .\) \(\frac{E^{2} L}{2 R}\)

The coefficient of mutual inductance between two coils depends upon:

Two coils have a mutual inductance of \(5\) mH. The current changes in the first coil according to the equation \(I=I_{0}\cos\omega t,\)where \(I_{0}=10~\text{A}\)and\(\omega = 100\pi ~\text{rad/s}\). The maximum value of emf induced in the second coil is:
1. \(5\pi\) Volt
2. \(2\pi\) Volt
3. \(4\pi\) Volt
4. \(\pi\) Volt

Eddy currents are used in:

1. Induction furnace

2. Electromagnetic brakes

3. Speedometers

4. All of these