Question

Magnetic induction on the equatorial line of a bar magnet is in the direction of magnetic moment.

• A. True
• B. False

Answer 1

The correct option is B False

The perpendicular bisector of the segment joining the north pole and south pole of a bar magnet is called equator of the magnet.

Here magnetic dipole moment

$M=m\times 2l$ and its direction from south pole to north pole, and P is a point on equatorial line and

$B_p=[\frac{{\mu }_0}{4\pi }\frac{m}{(r^2+l^2)}+\frac{{\mu }_0}{4\pi }\frac{m}{(r^2+l^2)}]\cos \theta$

$=\frac{{\mu }_{0}m}{4\pi (r^2+l^2)}\times \frac{l}{\sqrt{(r^2+l^2)}}$

$\{\because \cos \theta =\frac{oN}{oP}=\frac{l}{\sqrt{r^2+l^2}}\}$

$B_p=\frac{{\mu }_{0}M}{4\pi {(r^2+l^2)}^{\frac{3}{2}}}$

Its direction is from North pole to south pole.

Thus opposite in directions.