Question

Assertion : Magnetic force between two short magnets, when they are co-axial follows inverse square law of distance.
Reason : The magnetic forces between two poles do not follow inverse square law of distance

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true and reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

The correct option is D If both assertion and reason are false.

Force between two short magnets when they are co-axial $=\frac{B^2}{2{\mu }_0}A$

Where

A - contact surface area between two nearly touching magnets.

B - Magnetic induction in a very short gap between attracting magnets

${\mu }_0$ - permeability of free space.

Magnetic force between two poles $=\frac{\mu q_1{q}_2}{4\pi r^2}$

It does not follow inverse square law of distance. The assertion is false. The reason is also false.