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If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is
A
Attracted by both the poles
B
Repelled by both the poles
C
Repelled by the north pole and attracted by the south pole
D
Attracted by the north pole and repelled by the south pole
Detailed Solution
In a diamagnetic substance the atoms have no permanent magnetic moment.
When it is placed in an external magnetic field, a magnetic moment is induced in the direction opposite to the applied field (by Lenz's law).
Because the induced magnetisation always opposes the applied field, the substance tends to move from the stronger to the weaker part of the field.
The field is stronger near either pole, so the substance is pushed away from the north pole as well as from the south pole.
Hence it is repelled by both the poles.
When it is placed in an external magnetic field, a magnetic moment is induced in the direction opposite to the applied field (by Lenz's law).
Because the induced magnetisation always opposes the applied field, the substance tends to move from the stronger to the weaker part of the field.
The field is stronger near either pole, so the substance is pushed away from the north pole as well as from the south pole.
Hence it is repelled by both the poles.