Question

A long horizontal wire P carries a current of 50A. It is rigidly fixed. Another wire Q is placed directly above and parallel to P, as shown in Figure 1 below. The weight per unit length of the wire Q is 0.025 Nm-1 and it carries a current of 25A. Find the distance 'r' of the wire Q from the wire P so that the wire Q remains at rest

Answer 1

`F/l  = mu_0/(4pi)  (2I_1I_2)/r`

`0.025 = 10^(-7) xx (2xx50xx25)/r`

r = 0.01 m