Question

A short bar magnet has a magnetic moment of 0.39 J T-1. The magnitude and direction of the magnetic field produced by the magnet at a distance of 20 cm from the centre of the magnet on the equatorial line of the magnet is

• A. 0.049 G, N-S direction
• B. 4.95 G, S-N direction
• C. 0.0195 G, S-N direction
• D. 19.5 G, N-S direction

Answer 1

Answer: (A)

0.049 G, N-S direction

Answer 2

: Here,

On the equatorial line of magnet,

$= 10 ^ { - 7 } \times \frac { 0.39 } { ( 0.2 ) ^ { 3 } } = \frac { 0.39 \times 10 ^ { - 7 } } { 2 ^ { 3 } \times 10 ^ { - 3 } } = \frac { 0.39 } { 8 } \times 10 ^ { - 4 }$

$= 0.049 \times 10 ^ { - 4 }$T, N –S direction

$= 0.049$ G; N – S direction