Question

A freely suspended magnet rests in the geographic ________ direction.
A). North-west
B). North-south
C). East-west
D). West-north

Answer 1

Hint: Due to the rotation, the various charged ions present in the molten state, inside the core of the earth, rotate and this motion leads to a current. This current inside the earth’s crust generates a magnetic field.

Complete step by step answer:
Like a bar magnet earth also has its own magnetic field. The magnetic field of the earth is produced due to the rotation of the earth. When earth rotates, the various charged ions present in the molten state in the core of the earth rotate and this produces a current inside the earth.
The magnetic field of earth is as if a huge magnet is buried deep inside the earth at its centre and this magnet is producing the field. The axis of rotation of earth is called the geographic axis and the points where the geographical axis cuts the surface of earth are called geographical poles. These poles are called the geographic north (Ng) and the geographic south (Ng). The circle on the surface of the earth that is perpendicular to the geographical axis is called the equator.
A vertical plane through which the geographical axis passes is called geographical meridian.
The axis of the huge magnet, if assumed to be placed inside the earth, is called the magnetic axis of the earth. The magnetic poles are the points where the magnetic axis cuts the surface of earth. The circle on the surface of earth that is perpendicular to the magnetic axis is called the magnetic equator.
Geographical axis and magnetic axis do not coincide and they make an angle of 17.5 degrees with each other. Earth is divided by the magnetic equator into two hemispheres. The hemisphere in which the south polarity of earth’s magnetism lies is called the northern hemisphere and the hemisphere in which the north polarity lies is called the southern hemisphere. Earth’s magnetic field is not a constant value and changes irregularly from place to place on the earth and even at a given place varies with time. Direction of earth’s magnetic field is from S (geographical south) to N (geographical north). Therefore, when a magnet is freely suspended, it rests in the geographic north-south direction.
Hence, the correct option is (B).

Note: If we assume that the magnetic axis of the earth contains a huge magnet, then the north pole of this magnet is actually the south magnetic pole of the earth and the south pole is the north magnetic pole of the earth. The north pole of a freely suspended magnet points towards the south pole of this huge magnet and towards the north magnetic pole.