A copper wire with cross-sectional area S = 2.5 mm a bent to make three sides of

Question:

A copper wire with cross-sectional area S = 2.5 mm a bent to make three sides of a square can turn about a horizontal axis OO' (Fig. 3.69). The wire is located in uniform vertical magnetic field. Find the magnetic induction if on passing a current I = 16 A through the wire the latter deflects by an angle θ = 20°.