Magnetism and Matter · Question 36

In a uniform magnetic field of 0.049 T, a magnetic needle performs 20 complete oscillations in 5 seconds as shown. The moment of inertia of the needle is 9.8 10-6 kg m2. If the magnitude of magnetic moment of the needle is x 10-5 A m2, then the value of 'x' is : [figure]

1. 5 2
2. 128 2
3. 50 2
4. 1280 2

Match List I with List II Choose the correct answer from the options given below.

1. A-II, B-III, C-IV, D-I
2. A-II, B-I, C-III, D-IV
3. A-III, B-II, C-I, D-IV
4. A-IV, B-III, C-II, D-I

An iron bar of length L has magnetic moment M. It is bent at the middle of its length such that the two arms make an angle 60 with each other. The magnetic moment of this new magnet is :

1. M
2. M2
3. 2M
4. M 3

The magnetic potential energy, when a magnetic bar of magnetic moment m is placed perpendicular to the magnetic field B is

1. - mB2
2. Zero
3. -mB
4. mB

The incorrect relation for a diamagnetic material (all the symbols carry their usual meaning and is a small positive number) is

1. < 0
2. 0 r < 1
3. -1 < 0
4. 1 < r < 1 +

The magnetic moment and moment of inertia of a magnetic needle as shown are, respectively, 1.0 10-2 A m2 and 10-6 2 kg m2. If it completes 10 oscillations in 10 s, the magnitude of the magnetic field is [figure]

1. 0.4 T
2. 4 T
3. 0.4 mT
4. 4 mT

The magnetic moment of an iron bar is M. It is now bent in such a way that it forms an arc section of a circle subtending an angle of 60 at the centre. The magnetic moment of this arc section is

1. 3M
2. 4M
3. M
4. 2M

The net magnetic flux through any closed surface is :

1. Positive
2. Infinity
3. Negative
4. Zero

An iron rod of susceptibility 599 is subjected to a magnetizing field of 1200 A m-1. The permeability of the material of the rod is : ( 0 = 4 10-7 T m A-1)

1. 8.0 10-5 T m A-1
2. 2.4 10-5 T m A-1
3. 2.4 10-7 T m A-1
4. 2.4 10-4 T m A-1

At a point A on the earth’s surface the angle of dip, = +25 . At a point B on the earth's surface the angle of dip, = -25 . We can interpret that :

1. A is located in the southern hemisphere and B is located in the northern hemisphere.
2. A is located in the northern hemisphere and B is located in the southern hemisphere.
3. A and B are both located in the southern hemisphere.
4. A and B are both located in the northern hemisphere.