Question

A magnet is placed in earth's magnetic field with north pole of the magnet pointing north. At the neutral point

• A. The earth's magnetic field is zero
• B. The magnet's magnetic field is zero
• C. The net magnetic field is $0$
• D. The magnetic fields of the magnet and the earth are equal and opposite

Answer 1

Answer: (C), (D)

The correct options are
C The net magnetic field is $0$
D The magnetic fields of the magnet and the earth are equal and opposite

Answer is D.
As a result of two magnetic fields acting at the same place, the resultant field has a special feature. At a particular point, if the compass needle does not point in any particular direction, then there is no net magnetic field at the point. Such a point is called Neutral point or the Null point.
A neutral point is a point where the resultant magnetic field is zero.
At the point marked X in figure, the earth's magnetic field and the magnet's field are exactly equal and opposite and the resultant field is zero. These points are called the neutral points.