IIT JEE Advanced 2006 Paper 1

We see the following:
• FBC is perpendicular plane of the loop and it acts in the upward direction.
• FDA is perpendicular of the loop and it acts in the downward direction.
Therefore, the net force on the loop is zero.
FAB = FCD = 0
Now ,

→

J

= I

→

A

×

→

B

|

→

J

| = IAB sin θ
Here , θ = 90° , |

→

J

| = IAB ≠ 0.
As seen from the point O, the loop rotates in clockwise direction.