Magnetism Question 95

Question: The time period of a bar magnet suspended horizontally in the earth’s magnetic field and allowed to oscillate

[MP PET 1992]

Options:

A) Is directly proportional to the square root of its mass

B) Is directly proportional to its pole strength

C) Is inversely proportional to its magnetic moment

D) Decreases if the length increases but pole strength remains same

Show Answer

Answer:

Correct Answer: A

Solution:

$ T=2\pi \sqrt{\frac{I}{MB _{H}}},\text{and}\ I=\frac{\text{w}(l^{2}+b^{2})}{12};\ \ \

Therefore T\propto \sqrt{\text{w}} $ (w = Mass of the magnet)