Physics-Bar Magnet
NEET Physics Bar Magnet MCQ Question
Type: MCQ-numerical-Easy-Class 12
A bar magnet of length 2l and magnetic moment m is placed along the x-axis. If the magnetic field at a point on the axis of the magnet at a large distance d (where d >> l) from the center of the magnet is B, what is the relation between B and the magnetic moment m?
A
B ∝ m/d^3
B
B ∝ m/d^2
C
B ∝ m^2/d^3
D
B ∝ m^2/d^2
Correct Answer
Option A
Detailed Explanation
The magnetic field due to a bar magnet at large distances along its axis is proportional to the magnetic moment m divided by the cube of the distance, as derived from the electrostatic analog. Hence, B ∝ m/d^3.
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