Magnetism Question 163
Question: The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of x and y from the centre of the magnet is
[MP PMT 1990]
Options:
A) $ {{2}^{-3}} $
B) $ {{2}^{-1/3}} $
C) $ 2^{3} $
D) $ {{2}^{1/3}} $
Show Answer
Answer:
Correct Answer: D
Solution:
$ B _{1}=\frac{2M}{x^{3}}\ and\ B _{2}=\frac{M}{y^{3}} $ As $ B _{1}=B _{2} $ Hence $
$ $ \frac{2M}{x^{3}}=\frac{M}{y^{3}}\text{or}\frac{x^{3}}{y^{3}}=2\ \text{or}\ \frac{x}{y}={{2}^{1/3}} $
BETA
