When a bar magnet is placed at `90^(@)` to a uniform magnetic field, it is acted upon by a couple which is maximum. For the couple to be half of the maximum value, at what angle should the magnet be inclined to the magnetic field (B)?

Explanation

We know that , `tau = MB sin theta `
If ` theta = 90^(@) " then " tau_("max")=MB`........... (1)
From equation (1) and (2)
`2 = (1) sin theta or sin theta = (1)/(2) or theta = 30^(@)`