Figure shows a square loop ABCD with edge length a. The resistance of the wire ABC is r
and that of ADC is 2r. The value of magnetic field at the centre of the loop assuming
uniform wire is
1.
2.
3.
4.
A particle with charge q, moving with a momentum p, enters a uniform magnetic field normally. The magnetic field has magnitude B and is confined to a region of width d, where . The particle is deflected by an angle in crossing the field, then:
1. | \(\sin \theta={Bqd \over p}\) | 2. | \(\sin \theta={p \over Bqd}\) |
3. | \(\sin \theta={Bp \over qd}\) | 4. | \(\sin \theta={pd \over Bq}\) |
The unit vectors are as shown below. What will be the magnetic field at O in the following figure?
(a) (b)
(c) (d)
A current I is carried by an elastic circular wire of length L. It is placed in a uniform magnetic field B (out of paper) with its plane perpendicular to B's direction. What will happen to the wire?
\(F ~\)
1. | No force | 2. | A stretching force |
3. | A compressive force | 4. | A torque |
Two particles each of mass m and charge q are attached to the two ends of a light rigid rod of length 2R. The rod is rotated at constant angular speed about a perpendicular axis passing through its centre. The ratio of the magnitudes of the magnetic moment of the system and its angular momentum about the centre of the rod is:
1.
2.
3.
4.
Three long, straight parallel wires carrying current, are arranged as shown in figure. The force experienced by a 25 cm length of wire C is
(1)
(2)
(3) Zero
(4)
When a proton is released from rest in a room, it starts with an initial acceleration towards west. When it is projected towards north with a speed , it moves with an initial acceleration 3 towards west. The electric and magnetic fields in the room are
(a) mao/e west, 4mao/evo up
(b) mao/e west, 2mao/evo down
(c) mao/e east, 3mao/evo up
(d) mao/e east, 3mao/evo down
A long straight wire along the z-axis carries a current I in the negative z-direction. The magnetic field vector at a point having coordinates (x, y) in the z = 0 plane is :
1.
2.
3.
4.
A particle of charge q and mass m is moving along the x-axis with a velocity of v and enters a region of electric field E and magnetic field B as shown in the figure below. For which figure is the net force on the charge zero?
1. | 2. | ||
3. | 4. |
An electron, moving in a uniform magnetic field of induction of intensity has its radius directly proportional to :
(1) Its charge
(2) Magnetic field
(3) Speed
(4) None of these