A rod of length \(l\) rotates with a small but uniform angular velocity \(\omega\) about its perpendicular bisector. A uniform magnetic field \(B\) exists parallel to the axis of rotation. The potential difference between the centre of the rod and an end is:
1. zero
2. \(\frac{1}{8} \omega {B} l^{2}\)
3. \(\frac{1}{2} \omega {B} l^{2}\)
4. \(B\omega l^2\)
A rod of length \(l\) rotates with a uniform angular velocity \(\omega\) about its perpendicular bisector. A uniform magnetic field \(B\) exists parallel to the axis of rotation. The potential difference between the two ends of the rod is:
1. zero
2. \(\frac{1}{2}Bl\omega ^{2}\)
3. \(Bl\omega ^{2}\)
4. \(2Bl\omega ^{2}\)
Consider the situation shown in the figure. If the switch is closed and after some time it is opened again, the closed loop will show:
1. | an anticlockwise current-pulse. |
2. | a clockwise current-pulse. |
3. | an anticlockwise current-pulse and then a clockwise current-pulse. |
4. | a clockwise current-pulse and then an anticlockwise current-pulse. |
Solve the previous question if the closed loop is completely enclosed in the circuit containing the switch.
1. an anticlockwise current-pulse
2. a clockwise current-pulse
3. an anticlockwise current-pulse and then a clockwise current-pulse
4. a clockwise current-pulse and then an anticlockwise current-pulse.
Previous question: Consider the situation shown in figure. If the switch is closed and after some time it is opened again, the closed loop will show
A bar magnet is released from rest along the axis of a very long, vertical copper tube. After some time the magnet:
1. | will stop in the tube. |
2. | will move with almost constant speed. |
3. | will move with an acceleration \(g\). |
4. | will oscillate. |
The figure shows a horizontal solenoid connected to a battery and a switch. A copper ring is placed on a frictionless track, the axis of the ring being along the axis of the solenoid. As the switch is closed, the ring will:
1. | remain stationary |
2. | move towards the solenoid |
3. | moves away from the solenoid |
4. | move towards the solenoid or away from it depending on which terminal (positive or negative) of the battery is connected to the left end of the solenoid |
Consider the following statements:
(A): | An emf can be induced by moving a conductor in a magnetic field. |
(B): | An emf can be induced by changing the magnetic field. |
1. | Both A and B are True |
2. | A is True but B is False |
3. | B is True but A is False |
4. | Both A and B are False |
Consider the situation shown in the figure. The wire AB is slid on the fixed rails with a constant velocity. If the wire AB is replaced by a semicircular wire, the magnitude of the induced current will
1. increase
2. remain the same
3. decrease
4. increase or decrease depending on whether the-semicircle bulges towards the resistance or away from it
Figure (a) shows a conducting loop being pulled out of a magnetic field with a speed \(v\). Which of the four plots shown in Figure (b) may represent the power delivered by the pulling agent as a function of the speed \(v\)?
1. a
2. b
3. c
4. d
Two circular loops of equal radii are placed coaxially at some separation. The first is cut and a battery is inserted in between to drive a current in it. The current changes slightly because of the variation in resistance with temperature. During this period, the two loops:
1. | attract each other |
2. | repel each other |
3. | do not exert any force on each other |
4. | attract or repel each other depending on the sense of the current |