Question

Two long parallel wires, P and Q are fixed on a horizontal plane in north-south direction. Wire P is 10 cm left of Q. Wire P carries 40 A current northwards while wire Q carries 20 A current downwards. Determine the magnitude and direction of the resultant magnetic field at midpoint between the wires.

Answer 1

$F=\frac{\mu_0 I_1I_2}{2\pi d}=1.6~mN.$