A coil having number of turns N and cross-sectional area A is rotated in a uniform magnetic field B with an angular velocity $\mathrm{\omega }$. The maximum value of the emf induced in it is:

1. $\frac{\mathrm{NBA}}{\mathrm{\omega }}$                             

2. $\mathrm{NBA\omega }$

3. $\frac{\mathrm{NBA}}{{\mathrm{\omega }}^2}$                             

4. ${\mathrm{NBA\omega }}^2$

A long solenoid has 1000 turns. When a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4 x 10^-3 Wb. The self-inductance of the solenoid is:

1. 3 H

2. 2 H

3. 1 H

4. 4 H

A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is:

A coil has 500 turns and the flux through the coil is \(\phi=3t^{2} +4t+9\) milliweber. The magnitude of induced emf between the ends of the coil at t = 5 s is:

1. 34 millivolt

2. 17 volt

3. 17 millivolt

4. 34 volt

The current I in an inductance coil varies with time t according to the graph shown in the figure. Which one of the following plots shows the variation of voltage in the coil with time?

1.		2.
3.		4.

A bar magnet is released along the vertical axis of the conducting coil. The acceleration of the bar magnet is:

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:

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 R₀ is moving with speed v as shown in the figure. The current through the rod is:
               
1. $\frac{Blv}{{\displaystyle \frac{R_1{R}_2}{R_1+R_2}}+R_0}$

2. $\frac{\mathrm{Blv}}{{\left({\displaystyle \frac{1}{{\mathrm{R}}_1}}+{\displaystyle \frac{1}{{\mathrm{R}}_2}}+{\displaystyle \frac{1}{{\mathrm{R}}_{\mathrm{o}}}}\right)}^2}$

3. $\frac{Blv}{R_1+R_2+R_0}$

4. $\frac{Blv}{{\displaystyle \frac{1}{R_1}}+{\displaystyle \frac{1}{R_2}}+{\displaystyle \frac{1}{R_0}}}$