A long straight wire (wire 1) with a current of 3 amps runs in the -y direction.
ID: 1600974 • Letter: A
Question
A long straight wire (wire 1) with a current of 3 amps runs in the -y direction. Another long straight wire has a current of 3 amps running in -y direction and is located 2 meters to the right (+x direction) of wire 1. Another long straight wire has a current running in either the +y or -y direction and it is located 8 meters to the right (+x direction) of wire 1. The total force per unit length on the wire in the middle (wire 2) is 8 times 10^-6 N/m in the -x direction due to the two wires surrounding it. What is the amount and direction of the current in the third wire (wire on the furthest right.: wire 3) in amps? If the direction is -y, include a negative sign.Explanation / Answer
The total force per unit length on the wire in the middle is
F net /L = uo i1 i2/ 2pi d1 + uo i2 i3/ 2 pi d2
8.0 * 10^-6 N/m = 2 * 10^-7 ( 3) (3)/ 2 m + 2 * 10^-7 ( 3) i3/ 8 m
8.0 * 10^-6 - 9 * 10^-7 = 2 * 10^-7 (3) i3/ 8
i3 = 94.6A ( + y direction)