A conducting ring of radius r and resistance R rolls on a horizontal surface with constant velocity v. The magnetic field B is uniform normal to the plane of the loop.
1. The induced emf between O and Q is 2 Bvr
2. An induced current flows in the clockwise direction
3. An induced current flows in the anticlockwise
4. None
Two infinitely long straight wires AB and CD are placed side by side as shown in fig. AB carries a current i. If CD is moved towards AB, then
1. C will be at a higher potential
2. D will be at a higher potential
3. No e.m.f. is induced in CD
4. Force on CD will be away from AB
Two conducting rings of radii r and 3 r move in opposite directions with velocities 2 v and v respectively on a horizontal conducting surface. There is a uniform magnetic field of magnitude B perpendicular to the plane of the rings. The potential difference between the highest points of the two rings is
1. zero
2. 2 B rv
3. 6 B rv
4. 10 B rv
One conducting U tube can slide inside another as shown fig, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. if each tube moves towards the other at a constant speed v, then the emd induced in the circuit in terms of B,l and v (l is the width of each tube) will be
1. zero
2. 2 Blv
3. Blv
4. -Blv
A straight rod of length L is rotating about an axis passing through O and perpendicular to the plane. In the space, a uniform magnetic field B exists normal to the plane of rotation. Potential difference between P and Q is equal to
1.
2.
3.
4. zero
A conducting wire in the shape of Y with each side of length L is moving in a uniform field B with uniform speed V. The induced emf between P and Q of the wire will be
1. zero
2. 2 BLV
3. 2 BLV sin
4. 2 BLV sin
Switch S of the circiut shown in fig. is closed at t = 0. If denotes the induced e.m.f. in L and I the current flowing throught the circiut at time t, the which of the following graphs is correct?
1.
2.
3.
4.
An e.m.f. of 15 volt is applied in a circuit containing 5 henry inductance and 10 ohm resistance. The ratio of the current at time t = and t = 1 second is
1.
2.
3.
4.
A wire cd of length l and mass m is sliding without friction on conducting rails ax and by as shown. The vertical rails are connected to each other with resistance R between a and b. A uniform magnetic field B is applied perpendicular to the plane abcd such that cd moves with a constant velocity of
1.
2.
3.
4. None
In the circuit shown in fig, steady state current in the resistor R after the switch S is closed will be equal to
1. V/R
2. 2 V/3 R
3. V/3 R
4. V/2 R
In the following loop, which one of the following is correct expression for Kirchoff voltage law?
1.
2.
3.
4.
A rod of mass m and length l is placed on an inclined wedge of angle . The rails are connected by a resistance R on the other end. Find terminal velocity of the rod (B is vertically up)
1.
2.
3.
4.
Magnetic field in a cylindrical region is given by . Find emf across rod QP as shown in fig.
1.
2.
3.
4.
A uniform magnetic field is confined in a cylindrical region of radius R. Induction of magnetic field is increasing at a constant rate . Strength of induced electric field (E) varies with distance r from the axis of cylindrical region as -
1.
2.
3.
4.
In the given branch AB of a circuit, a current I = (10t+5) A is flowing, where t is time in second.At t = 0, the potential difference between points A and B
1. 15 V
2. -5 V
3. -15 V
4. 5 V