Current in a circuit falls from \(5.0\) A to \(0\) A in \(0.1~\text{s}\). 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
A pair of adjacent coils has a mutual inductance of \(1.5\) H. If the current in one coil changes from \(0\) to \(20\) A in \(0.5\) s, what is the change of flux linkage with the other coil?
1. | \(35\) Wb | 2. | \(25\) Wb |
3. | \(30\) Wb | 4. | \(20\) Wb |
What is the dimensional formula of magnetic flux?
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. \(\frac{L}{4}\)