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# A rectangular loop carrying a current is situated near a long straight wire as shown. If a current $i$ now starts flowing through the wire, the loop will

$\begin {array} {1 1} (a)\;Move \: away \: from\: the\: wire & \quad (b)\;Move\: towards\: the\: wire \\ (c)\;Rotate\: about \: an \: axis\: parallel\: to\: the\: wire & \quad (d)\;Remain \: stationary \end {array}$

For the loop, using Lenz’s Law, the force on the part which is nearer, due to the current in the long wire is attraction and force on the part which is farther is repulsion.
F (atttaction) > F(repulsion)
hence loop moves towards the wire
Ans : (b)

edited Sep 16, 2014