If the moment of a magnet is `0.4 A m^(-1)` and force seting on esch pote in a uniform magnetic field of induction `3.2 xx 10^(-5)"Wb/m"^(2)" is "5.12 xx 10^(-5)N,` the dstance berween the poles of magnet is

Options

A. 25 cm
B. 16cm
C. 12.5cm
D. 12cm

Answer

A

Explanation

`M=-0.4 Am^(2),F=5.12xx10^(-5)N,B=3.2xx10^(-5)T,2l=?`
`M=m.2l(B=(F)/(m))`
`M=(F)/(B).2l`
`therefore 2l =(MB)/(F)=(0.4xx3.2xx10^(-5))/(5.12xx10^(-5))=25cm`