Q. No.A long solenoid with 15 turns cm has a small loop of area 2.0 cm2 placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from 2.0 A to 4.0 A in 0.1 s, what is the induced emf in the loop while the current is changing?
| 1. | 7.5×10−6 V | 2. | 6.5×10−6 V |
| 3. | 7.5×10−5 V | 4. | 6.5×10−5 V |
A 1 m long metallic rod is rotating with an angular frequency of 400 rad/s about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of 0.5 T parallel to the axis exists everywhere. The emf induced between the centre and the ring is:
1. 200 V
2. 100 V
3. 50 V
4. 150 V
A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad/s in a uniform horizontal magnetic field of magnitude 3×10-2 T. The maximum emf induced in the coil is:
1. 0.603 V
2. 0.01 V
3. 0
4. 1 V
| 1. | 2.5×10−3 V | 2. | 1.5×10−4 V |
| 3. | 2.5×10−4 V | 4. | 1.5×10−3 V |
Current in a circuit falls from 5.0 A to 0 A in 0.1 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 rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of the uniform magnetic field of magnitude 0.3 T directed normally to the loop. What is the EMF developed across the cut if the velocity of the loop is 1 cm/s in a direction normal to the longer side?
1. 2.4×10−4 V
2. 2.0×10−3 V
3. 1.3×10−4 V
4. 1.7×10−3 V
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 |
1. 2.712 V
2. 3.125 V
3. 1.112 V
4. 3.011 V
If a loop changes from an irregular shape to a circular shape, then magnetic flux linked with it:
1. decreases
2. remains constant
3. first decreases and then increases
4. increases
It is desired to measure the magnitude of the field between the poles of a powerful loudspeaker magnet. A small flat search coil of area 2 cm2 with 25 closely wound turns, is positioned normal to the field direction, and then quickly snatched out of the field region. Equivalently, one can give it a quick 90° turn to bring its plane parallel to the field direction). The total charge flown in the coil (measured by a ballistic galvanometer connected to the coil) is 7.5 mC. The combined resistance of the coil and the galvanometer is 0.50 Ω. The field strength of the magnet is:
1. 0.55 T
2. 0.75 T
3. 0.67 T
4. 0.49 T
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