A magnetic needle is suspended first at the earth's north magnetic pole and then at a point on the magnetic…

Analyze the question We need the angle of dip (inclination), which is the angle a freely suspended magnetic needle makes with the horizontal, at two places: the magnetic pole and the magnetic equator.

Concept The earth's magnetic field lines leave and enter the earth like those of a bar magnet:

• At the magnetic poles, the field lines are vertical (pointing into or out of the earth). A freely suspended needle therefore points straight down, making an angle of 90° with the horizontal.
• At the magnetic equator, the field lines run parallel to the earth's surface, so the needle lies horizontal, making an angle of 0° with the horizontal.

This angle is called the angle of dip, or magnetic inclination.

Solution

• At the north magnetic pole: dip = 90°
• At the magnetic equator: dip = 0°

The respective angles are therefore 90° and 0°.

Checking the options:

• A (0° and 0°): wrong, because the needle is vertical at the pole.
• B (60° and 60°): wrong, because 60° is not the dip at either location.
• C (90° and 90°): wrong, because the needle is horizontal at the equator.
• D (90° and 0°): correct.

Tip Remember "Pole = Perpendicular (90°), Equator = Even/flat (0°)". The dip increases from 0° at the magnetic equator to 90° at the magnetic poles.