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

The relation amongst the three elements of Earth's magnetic field, namely horizontal component H, vertical component V and dip angle$\delta$ is: ($B_E$=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$\delta$ 

If ${\theta }_1$ and ${\theta }_2$ are the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip $\theta$ is given by:
1. ${\tan }^2\theta ={\tan }^2{\theta }_1+ta{n}^2{\theta }_2$
2. $co{t}^2\theta =co{t}^2{\theta }_1-co{t}^2{\theta }_2$
3. ${\tan }^2\theta ={\tan }^2{\theta }_1+ta{n}^2{\theta }_2$
4. $co{t}^2\theta =co{t}^2{\theta }_1+co{t}^2{\theta }_2$

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