The couple acting on a magnet of length 10cm and pole strength 15A-m, kept in a field of `B=2xx10^(-5)`, at an anlge of `30^(@)` is

Options

A. `1.5 xx 10^(-5) Nm`
B. `1.5 xx 10^(-3) N-m`
C. `1.5 xx 10^(-2) N-m`
D. `1.5 xx 10^(-6) N-m`

Answer

A

Explanation

As, `tau = MB sin theta`
`tau =(m xx 2I) xx xx 10^(-5) sin 30^(@)`
`tau = 15 xx 10 xx 10^(-2) xx 2 xx 10^(-5) xx 1/2`
`tau = 1.5 xx 10^(-5) Nm`