A bar magnet of length 6 cm has a magnetic moment of $$4\ \text{J T}^{-1}$$. Find the strength of magnetic field at a distance of 200 cm from the centre of the magnet along its equatorial line.

A

$$4 \times 10^{-8}$$ tesla

B

$$3.5 \times 10^{-8}$$ tesla

C

$$5 \times 10^{-8}$$ tesla

D

$$3 \times 10^{-8}$$ tesla