A wire of c.s.S = `2.5 mm^(2)` is bent to make the three sides of a square and is free to turn about the horizontal axis `infity` Find the magnetic induction B which is vertically upward if the frame is deflected by `theta=30^@)` from the vertical when a current I=16A is passed through the wire. The density of the wire `sigma=8900 kgm^(-3)`