Question

When a Magnetic needle is suspended freely, it always aligns itself in the direction of the magnetic north-pole and south-pole of the earth, the north pole of the needle gets attracted towards the magnetic south pole of the earth and the south gets repelled equally away from it. So two equal and opposite forces acting on the needle should cancel each other which does not happen because of the:
A. Force of attraction and repulsion are equal but not in the exact opposite direction
B. Force of attraction and repulsion are not exactly equal even they are in the opposite direction
C. Force of attraction is repulsion are not equal and not the opposite direction
D. Force of attraction and repulsion are exactly equal and opposite in direction

Answer 1

The earth acts as a magnetic bar. A magnetic bar has both positive and negative terminals. Hypothetically it is assumed that the field lines of the magnet originate from the positive terminal (north-pole) and go to the negative terminal (south-pole). The magnetic field line never overlaps each other.

Complete step-by-step answer:
The core of the earth has its magnetization property. The core of the earth generates its magnetic field, which sustains the main part of the field which we measure on the surface of the earth. Earth itself behaves like a bar magnet.
When a magnetic needle is freely suspended over the earth the soul-pole of the magnetic needle is attracted towards the north pole of the earth and the north pole of the magnet is attracted towards the south pole of the magnet.
The intensity of the magnetic field of the pole of the earth increases as we move near to the pole and decreases as we move away from the pole. This difference cannot be noticed over a small range of distance. But this can be seen for the larger range and it does have an impact on the freely suspended magnetic materials on the earth.
Due to this reason only though the magnetic poles are exactly opposite to each other they can nullify each other.
Thus, from the above discussion, it can be said that the correct option which states the correct explanation to the condition mentioned in the question is Option B.

So, the correct answer is “Option B”.

Note: Magnetic field lines are used as tools to represent the magnetic field. The intensity of the magnetic field can be determined by the space between the two successive field lines. Denser the field lines higher is the magnetic field intensity. As we move away from the poles magnetic field intensity decreases.