Magnetism Question 222
Question: A bar magnet has a length 8 cm. The magnetic field at a point at a distance 3 cm from the centre in the broad side-on position is found to be $ 4\times {{10}^{-6}}T $ . The pole strength of the magnet is.
Options:
A) $ 6\times {{10}^{-5}}Am $
B) $ 5\times {{10}^{-5}}Am $
C) $ 2\times {{10}^{-4}}Am $
D) $ 3\times {{10}^{-4}}Am $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Magnetic field due to a bar magnet in the broad-side on position is given by $ B=\frac{{\mu _{0}}}{4\pi }\frac{M}{[ r^{2}+\frac{{{\ell }^{2}}}{4} ]};M=m\ell $ . After substituting the values and simplifying we get $ B=6\times {{10}^{-5}},A-m $
BETA
