A long solenoid with \(15\) turns per 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. | \(7.5 \times 10^{-6}~ \text{V}\) | 2. | \(6.5 \times 10^{-6}~\text{V}\) |
3. | \(7.5 \times 10^{-5}~\text{V}\) | 4. | \(6.5 \times 10^{-5}~\text{V}\) |
A \(1~\text{m}\) long metallic rod is rotating with an angular frequency of \(400~\text{rad/s}\) 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 \(0.5~\text{T}\) parallel to the axis exists everywhere. The emf induced between the centre and the ring is:
1. \(200~\text{V}\)
2. \(100~\text{V}\)
3. \(50~\text{V}\)
4. \(150~\text{V}\)
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 The maximum emf induced in the coil is:
1. 0.603 V
2. 0.01 V
3. 0
4. 1 V
1. | \(2.5 \times 10^{-3} ~\text V\) | 2. | \(1.5 \times 10^{-4} ~\text V\) |
3. | \(2.5 \times 10^{-4}~\text V\) | 4. | \(1.5 \times 10^{-3} ~\text V\) |
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 rectangular wire loop of sides \(8~\text {cm}\) and \(2~\text{cm}\) with a small cut is moving out of a region of the uniform magnetic field of magnitude \(0.3~\text T\) directed normally to the loop. What is the EMF developed across the cut if the velocity of the loop is \(1~\text{cm/s}\) in a direction normal to the longer side?
1. \(2.4 \times10^{-4}~\text V\)
2. \(2.0 \times10^{-3}~\text V\)
3. \(1.3 \times10^{-4}~\text V\)
4. \(1.7 \times10^{-3}~\text V\)
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 |
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 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 . The field strength of the magnet is:
1. 0.55 T
2. 0.75 T
3. 0.67 T
4. 0.49 T