Work done in increasing the current through a solenoid from \(0\) to \(2\) A is \(20\) J. Work done in increasing the current from \(4\) A to \(6\) A is:

1.	\(100\) J	2.	\(60\) J
3.	\(80\) J	4.	\(120\) J

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:

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 a speed \(v\) as shown in the figure. The current through the rod is:
                            

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

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

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

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

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. \(5\pi~\text{V}\)
2. \(2\pi~\text{V}\)
3. \(4\pi~\text{V}\)
4. \(\pi~\text{V}\)

A short magnet is allowed to fall along the axis of a horizontal metallic ring. Starting from rest, the distance fallen by the magnet in one second may be: