A square loop of side l is kept in a uniform magnetic field B such that its plane makes an angle α with vecB. The loop carries a current i. The torque experienced by the loop in this position is

Question

A square loop of side l is kept in a uniform magnetic field B such that its plane makes an angle α with vecB. The loop carries a current i. The torque experienced by the loop in this position is (A) B i l2 (B) B i l2 sin α (C) B i l2 cos α (D) Zero

Tardigrade Admin · Accepted Answer

τ= vecM × vecB vecM=i A=i l2 ⇒ τ=i l2 sin (90-α) =B i l2 cos α

Q. A square loop of side $l$ is kept in a uniform magnetic field $B$ such that its plane makes an angle $α$ with $B$ . The loop carries a current $i$ . The torque experienced by the loop in this position is

$B i l^{2}$

$B i l^{2} sin α$

$B i l^{2} cos α$

Zero

$τ = M \times B$
$M = i A = i l^{2}$
$\Rightarrow τ = i l^{2} sin (90 - α)$
$= B i l^{2} cos α$

Q. A square loop of side l is kept in a uniform magnetic field B such that its plane makes an angle α with B. The loop carries a current i. The torque experienced by the loop in this position is

Bil2

Bil2sinα

Bil2cosα