Moving Charges and Magnetism · Question 9

A wire carrying a current I along the positive x-axis has length L. It is kept in a magnetic field B = (2 i + 3 j - 4 k) T. The magnitude of the magnetic force acting on the wire is :

1. 5 IL
2. 5 IL
3. 3 IL
4. 3 IL

A very long conducting wire is bent in a semi-circular shape from A to B as shown in figure. The magnetic field at point P for steady current configuration is given by : [figure]

1. 0 i4R pointed away from the page
2. 0 i4R [1 - 2 ] pointed away from page
3. 0 i4R [1 - 2 ] pointed into the page
4. 0 i4R pointed into the page

A long solenoid of radius 1 mm has 100 turns per mm. If 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is

1. 6.28 10-2 T
2. 12.56 10-2 T
3. 12.56 10-4 T
4. 6.28 10-4 T

Given below are two statements: In light of above statements choose the most appropriate answer from the options given below.

1. Both Statement I and Statement II are correct
2. Both Statement I and Statement II are incorrect
3. Statement I is correct and Statement II is incorrect
4. Statement I is incorrect and Statement II is correct

From Ampere's circuital law for a long straight wire of circular cross-section carrying a steady current, the variation of magnetic field in the inside and outside region of the wire is

1. Uniform and remains constant for both the regions.
2. A linearly increasing function of distance upto the boundary of the wire and then linearly decreasing for the outside region.
3. A linearly increasing function of distance r upto the boundary of the wire and then decreasing one with 1r dependence for the outside region.
4. A linearly decreasing function of distance upto the boundary of the wire and then a linearly increasing one of the outside region.

A closely packed coil having 1000 turns has an average radius of 62.8 cm. If current carried by the wire of the coil is 1 A, the value of magnetic field produced at the centre of the coil will be (permeability of free space = 4 10-7 H/m) nearly

1. 10-3 T
2. 10-1 T
3. 10-2 T
4. 102 T

The shape of the magnetic field lines due to an infinite long, straight current carrying conductor is

1. a plane
2. a straight line
3. circular
4. elliptical

Two very long, straight, parallel conductors A and B carry current of 5 A and 10 A respectively and are at a distance of 10 cm from each other. The direction of current in two conductors is same. The force acting per unit length between two conductors is : ( 0 = 4 10-7 SI unit)

1. 1 10-4 N m-1 and is repulsive
2. 2 10-4 N m-1 and is attractive
3. 2 10-4 N m-1 and is repulsive
4. 1 10-4 N m-1 and is attractive

The magnetic field on the axis of a circular loop of radius 100 cm carrying current I = 2 A, at point 1 m away from the centre of the loop is given by :

1. 6.28 10-4 T
2. 3.14 10-7 T
3. 6.28 10-7 T
4. 3.14 10-4 T

A thick current carrying cable of radius 'R' carries current 'I' uniformly distributed across its cross section. The variation of magnetic field B(r) due to the cable with the distance 'r' from the axis of the cable is represented by :

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