A magnet of magnetic moment `50 hat(i) A-m^(2)` is placed along the x-axis in a magnetic field `vec(B)=(0.5hat(i)+3.0hat(j))T`. The torque acting on the magnet is

Options

A. `175 hat(k) N- m`
B. `150 hat(k) N- m`
C. `75 hat(k) N- m`
D. `25 sqrt37 hat(k) N- m`

Answer

B

Explanation

`tau= vec(m) xx vec(B) = (50 hat(i)) xx (0.5 hat(i) + 3.0 hat(j)) = 25 xx 0 + 150 hat(k)= 150 hat(k) Nm`