Moving Charges and Magnetism · Question 13

The magnetic field at the centre of a current carrying circular loop of radius R is 16 . The magnetic field at a distance x = 3R on its axis from the centre is .

1. 8
2. 2
3. 4
4. 2 2

Three long straight wires carrying current are arranged mutually parallel as shown in the figure. The force experienced by 15 cm length of wire Q is . ( 0 = 4 10-7 T m/A) [figure]

1. 6 10-6 N towards P
2. 6 10-6 N towards R
3. 6 10-7 N towards P
4. 6 10-7 N towards R

A long cylindrical conductor with large cross section carries an electric current distributed uniformly over its cross-section. Magnetic field due to this current is: Choose the correct answer from the options given below:

1. B, C Only
2. E Only
3. A, D Only
4. D Only

A moving coil galvanometer of resistance 100 shows a full scale deflection for a current of 1 mA. The value of resistance required to convert this galvanometer into an ammeter, showing full scale deflection for a current of 5 mA, is

1. 25
2. 2.5
3. 0.5
4. 10

Two identical circular loops P and Q each of radius r are lying in parallel planes such that they have common axis. The currents through P and Q are I and 4I respectively in clockwise direction as seen from O. The net magnetic field at O is : [figure]

1. 0 I4 2r towards Q
2. 3 0 I4 2r towards Q
3. 3 0 I4 2r towards P
4. 0 I4 2r towards P

The current passing through a conducting loop in the form of equilateral triangle of side 4 3 cm is 2 A. The magnetic field at its centroid is 10-5 T. The value of is . (Given: 0 = 4 10-7 SI units)

1. 3 3
2. 2 3
3. 3
4. 32

A current carrying solenoid is placed vertically and a particle of mass m with charge Q is released from rest. The particle moves along the axis of solenoid. If g is acceleration due to gravity then the acceleration (a) of the charged particle will satisfy :

1. a > g
2. a = 0
3. 0 < a < g
4. a = g

An infinitely long straight wire carrying current I is bent in a planar shape as shown in the diagram. The radius of the circular part is r. The magnetic field at the centre O of the circular loop is : [figure]

1. - 02 Ir( + 1) i
2. - 02 Ir( - 1) i
3. 02 Ir( + 1) i
4. 02 Ir( - 1) i

Figure shows a current carrying square loop ABCD of edge length 'a' lying in a plane. If the resistance of the ABC part is r and that of ADC part is 2r, then the magnitude of the resultant magnetic field at centre of the square loop is [figure]

1. 2 0 I3 a
2. 2 0 I3 a
3. 3 0 I 2a
4. 0 I2 a

A particle of charge q, mass m and kinetic energy E enters a magnetic field perpendicular to its velocity and undergoes a circular arc of radius (r). Which of the following curves represents the variation of r with E?

1. [figure]
2. [figure]
3. [figure]
4. [figure]