What is the dimensional formula of magnetic flux?
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2.
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4.
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 e.m.f. |
4. | Both an e.m.f. 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 e.m.f. 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. |
The magnetic energy stored in a long solenoid of an area of cross-section A in a small region of length L is:
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2.
3.
4.
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.
2. 2L
3. L
4.
With the decrease of current in the primary coil from 2 A to zero in 0.01 s, the e.m.f. generated in the secondary coil is \(1000~\mathrm{V}\). The mutual inductance of the two coils is:
1. 1.25 H
2. 2.50 H
3. 5.00 H
4. 10.00 H
Two coaxial coils are very close to each other and their mutual inductance is 5 mH. If a current 50 sin 500t is passed in one of the coils, then the peak value of induced e.m.f. in the secondary coil will be:
1. | 5000 V | 2. | 500 V |
3. | 150 V | 4. | 125 V |