Q.
The distance between the poles of a horse shoe magnet is $0.1\ m$ and its pole strength is $0.01\ amp$-$m$. The induction of magnetic field at a point midway between the poles will be
A) $2 \times 10^{- 5}T$
B) $4 \times 10^{- 6}T$
C) $8 \times 10^{- 7}T$
D) Zero
Explanation
(c) Net magnetic field at mid point $P,\ B = B_{N} + B_{S}$
where $B_{N} =$ magnetic field due to $N$-pole
$B_{S} =$ magnetic field due to $S$-pole
[image:5_image29.png]
$B_{N} = B_{S} = \frac{\mu_{0}}{4\pi}\frac{m}{r^{2}}$
$= 10^{- 7} \times \frac{0.01}{\left( \frac{0.1}{2} \right)^{2}} = 4 \times 10^{- 7}T$
$\therefore B_{net} = 8 \times 10^{- 7}T$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.