Question

Derive an expression for magnetic field due to a bar magnet at a point along its equator .​

Answer 1

Explanation:

Consider a point P on equatorial (or broad side on position) of short bar magnet of length 2I, having north pole (N) and south pole (S) of strength +q

m

and −q

m

respectively. The distance of point P from the mid-point (O) of magnet is r. Let B

1

and B

2

be the magnetic field intensities due to north and south poles respectively. NP=SP=

r

2

+l

2

.

vecB

1

=

4π

μ

0

r

2

+l

2

q

m

along N to P

vecB

2

=

4π

μ

0

r

2

+l

2

q

m

along P to S

Clearly, magnitude of and are equal

i.e., ∣

B

1

∣=∣

B

2

∣ or B

1

=B

2