Consider three long straight parallel wires as shown in figure. The force experienced by a 25 cm length of wire C is n × 10-4N. Find the value of n?

Repulsion by wire D,F1=μ02πi1i2lr[towards right] =2×10-7(30×10)3×10-2(0.25)=5×10-4 N Repulsion by wire G, =F2=2×10-7(20×10)5×10-2(0.25)=2×10-4 N ∴Fnet =F1-F2=3×10-4 N