A very long straight wire carries current of 20 A in directi

A very long straight wire carries current of 2.0 A in direction up, along z-axis. Its location in x-y plane is (2.0m, 0.0m). Second long straight wire carries current of 1.5 A down, along z-axis. Its location in x-y plane is (0.0m, 3.0m). Start with a sketch of the x-y plane. Find magnitude of the force which the first wire exerts on the 0.20 m of the second wire. Is this force attractive or repulsive, and how can you tell? Work it out using RHR for the magnetic force on a current-carrying wire. Please write out step by step and explain.

Solution

distance between the wires is r = sqrt(2^2+3^2) = 3.6 m

Force on second wire F = mu_o*i1*i2*l/(2*pi*r) = (2*10^-7*2*1.5*0.2)/(3.6) = 3.33*10^-8 N

since two currents are in opposite directions,they repel each other