Question

Find the magnitude and direction of a force vector acting on a unit length of a thin wire, carrying a current I = 8.0 A, at a point O, if the wire is bent as shown in 

(a) Fig. 3.68a, with curvature radius R = 10 cm; 

(b) Fig. 3.68b, the distance between the long parallel segments of the wire being equal to l = 20 cm.

Answer 1

(a) The magnetic field at O is only due to the curved path, as for the line element, 

(b) In this part, magnetic induction vector B at O will be effective only due to the two semi infinite segments of wire. Hence

Thus force per unit length,