The force acting on a north pole of magnet of pole strength 3200 Am and 10 cm away from the south pole of a point bar magnet of pole strength 40 Am is .......... N.

Options

A. `-1.28`
B. `1.28`
C. `1.28 xx 10^(-7)`
D. `1.28 xx 10^(-7)`

Answer

B

Explanation

`F= (mu_0)/( 4pi ) . (p_1 p_2)/( r^2)`
`= 10^(-7) xx (3200 xx 40)/((0.1)^(2))`
`=12800000 xx 10^(-7) `
`therefore F=1.28 N`