The relations amongst the three elements of Earth's magnetic field, namely horizontal component H, vertical component V and  dip angle $\delta$ are, ($B_E$=total magnetic field)

(1) V=$B_E$ tan $\delta$, H=$B_E$

(2) V=$B_E$ sin$\delta$, H=$B_E$ cos$\delta$

(3) V=$B_E$ cos $\delta$, H=$B_E$ sin $\delta$

(4) V=$B_E$, H=$B_E$ tan$\delta$ 

Electromagnets are made of soft iron because soft iron has

1. low retentivity and high coercive force

2. high retentivity and high coercive force

3. low retentivity and low coercive force

4. high retentivity and low coercive force

A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It

1. will become rigid showing no movement

2. will stay in any position

3. will stay in north-south direction only

4. will stay in east-west direction only

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

1. A and B are both located in the southern hemisphere.

2. A and B are both located in the northern hemisphere.

3. A is located in the southern hemisphere and B is located in the northern hemisphere.

4. A is located in the northern hemisphere and B is located in the southern hemisphere.

A vibration magnetometer placed in a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2s in earth's horizontal magnetic field of 24 $\mu$T. When a horizontal field of 18 $\mu$T is produced opposite to the earth's field by placing a current-carrying wire, the new time period of the magnet will be

1. 1s

2. 2s

3. 3s

4. 4s

The magnetic susceptibility is negative for

1. paramagnetic material only

2. ferromagnetic material only

3. paramagnetic and ferromagnetic materials

4. diamagnetic material only