Question

Magnetism at the centre of a bar magnet
(A). Minimum
(B). Maximum
(C). Zero
(D). Minimum or maximum

Answer 1

- Hint: Bar magnets as the name suggests are like bars that are rectangular in shape. Magnets have a north pole and south pole. These areas have the strongest magnetism and the magnetism reduces as you move towards the centre.

Complete step-by-step solution -
Bar magnet is an artificially made material made of iron or steel and shaped in the form of a bar, having permanent magnetic properties. A bar magnet has, like any other magnetic object two poles, namely north and south at two ends of the bar. If a bar magnet is broken into smaller pieces, every individual piece will have two poles. This suggests that the compound magnet is composed of smaller magnets, with every pole cancelling the adjacent opposite pole. This leaves only the poles at the ends of the bar magnet, where the magnetic field is the strongest. In a bar magnet the magnetic dipoles are oriented in a particular direction, from the south pole to the north pole. These dipoles are able to hold their position giving the bar magnet its permanent magnetic property. As for the centre of the bar magnet, if we consider a plane passing through the centre, there would be equal number of dipoles on each side, with opposite polarities. As such the magnetic field cancels out, it leaves zero net magnetic field at the centre.

Hence, the correct option is C.

Additional information:
The magnetic field lines run parallel through the bar magnet and diverge at the poles.

As we can see the magnetic field lines start from one pole and terminate at another, so magnetism is high in these poles. It can also be seen that the magnetic field lines are parallel to centre hence the magnetism effect nullifies at the centre.

Note: Actually, the above description fits a very ideal case. Due to imperfections, or different orientations and uneven distribution of magnetic dipoles, the field at the centre would be finite non-zero.