A rectangular coil of 100 turns has length 5 cm and width 4 cm. it is placed with its plane parallel to a uniform magnetic field and a current of 2 A is sent through the coil. Find the magnitude of the magnetic field B, if the torque acting on the coil is `0.2 Nm^(-1).`

Explanation

`tau = nia xx B`
`tau = niBa sin 90^@`
`rArr 0.2 = 100 xx 2 xx 5 xx 4 xx 10^(-4) xx b rArr b = 0.5 tesla`