Question

When $N$-pole of the given bar magnet is placed on a table pointing geographic north, the null points are formed due to the superposition of the magnetic field of the bar magnet and the earths magnet. The two null points are located :

• A. on the axial line at equidistant points on either sides
• B. on the equatorial line at equidistant points on either sides
• C. on the axial line only on one side of the magnet
• D. on the equatorial line only on one side of the magnet

Answer 1

Answer: (B)

on the equatorial line at equidistant points on either sides

The magnetic south pole of the earth's magnetic field is at the geographic north pole and the magnetic north pole is at the geographic south.
The magnetic field lines flow from north to south outside the magnet and south to north outside the magnet.
When the north pole of bar magnet points geographic north , the null points are formed on the equatorial line because magnetic field lines are from the bar magnet from north to south are cancelled by the magnetic field lines by the earth's magnet . The two null points are located on the equatorial line at equidistant points on either sides.

Hence, option B is correct.