Q. No.Current in a circuit falls from \(5.0~\text A\) to \(0~\text A\) in \(0.1~\text{s}\). If an average emf of \(200~\text V\) is induced, the self-inductance of the circuit is:
1. \(4~\text H\)
2. \(2~\text H\)
3. \(1~\text H\)
4. \(3~\text H\)
1. \(4~\text H\)
2. \(2~\text H\)
3. \(1~\text H\)
4. \(3~\text H\)
A pair of adjacent coils has a mutual inductance of \(1.5~\text H.\) If the current in one coil changes from \(0\) to \(20~\text A\) in \(0.5~\text s,\) what is the change of flux linkage with the other coil?
| 1. | \(35~\text{Wb}\) | 2. | \(25~\text{Wb}\) |
| 3. | \(30~\text{Wb}\) | 4. | \(20~\text{Wb}\) |
1. \(\left[ M L^2 T^{-2}A^{-1}\right]\)
2. \(\left[ M L^1 T^{-1}A^{-2}\right]\)
3. \(\left[ M L^2 T^{-3}A^{-1}\right]\)
4. \(\left[ M L^{-2} T^{-2}A^{-2}\right]\)
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:
| 1. | No current |
| 2. | A current |
| 3. | Only an emf |
| 4. | Both an emf and a current |
The magnetic flux through a coil varies with time \(t\) as shown in the diagram. Which graph best represents the variation of the emf \(E\) 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:
| 1. | \(a\) | 2. | \(b\) |
| 3. | \(c\) | 4. | \(d\) |
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:
| 1. | parallel to the motion of wire. |
| 2. | along with \(XY\). |
| 3. | perpendicular outside the paper. |
| 4. | perpendicular inside the paper. |
| 1. | \(\dfrac{B^{2} AL}{2\mu_{0}^{2}}\) | 2. | \(\dfrac{AL}{2 \mu_{0}}\) |
| 3. | \(\dfrac{1}{2} \mu_{0} B^{2} AL\) | 4. | \(\dfrac{B^{2} AL}{2 \mu_{0}}\) |
An inductor is connected to a direct voltage source through a switch. Then:
| 1. | a very large emf is induced in inductor when the switch is closed. |
| 2. | a large emf is induced when the switch is opened. |
| 3. | a large emf is induced whether the switch is closed or opened. |
| 4. | no emf is induced whether the switch is closed or opened. |
A long solenoid has self-inductance \(L\). If its length is doubled keeping total number of turns constant, then its new self-inductance will be:
1. \(\frac{L}{2}\)
2. \(2L\)
3. \(L\)
4. \(\frac{L}{4}\)
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