Question

At a neutral point in the neighbourhood of a bar magnet placed in earth’s magnetic field:
A. The magnetic field of the magnet is zero
B. The fields of the earth and the magnet are equal in magnitude and oppositely directed
C. A magnetic compass needle will point perpendicular to the bar magnet
D. A magnet compass needle will align, itself parallel to the bar magnet

Answer 1

Magnetic field is the field around the moving charges which in result other magnetic substances get either attracted or repelled by the magnetic force. Earth’s magnetic field which arises from earth’s interior core into outer space and re-enter earth's interior on the opposite side, this earth’s magnetic field is also known as geomagnetic field.

Complete answer:
First we need to know about neutral points. A point in space where the net magnetic field is zero that particular point is known as a neutral point. A neutral point exists when the magnetic field of the magnet is neutralized with the horizontal component of earth’s magnetic field and this occurs only when the magnitude of magnetic field of the magnet and the magnitude of earth’s magnetic field in horizontal direction are equal but their directions are opposite to each other. So, to exist as a neutral point, the magnitude of magnetic field is equal to both earth’s horizontal component and magnetic field of magnet but opposite in direction.

Hence, the correct option is B.

Note: It should be remembered that, magnetic field is not something physical in nature but it’s the effect that can be seen and observed. A bar magnet consists of north and south poles in it, the direction of magnetic field is from North pole to South pole outside the bar magnet but inside the magnet the direction of magnetic field is from South pole to North pole, the SI unit in which magnetic field is measured is Tesla.