Question

Two long parallel wires are separated by a distance of 2.50 cm. The force per unit length that each wire exerts on the other is 4.00xx10^-5 N/m, and the wires repel each other. The current in one wire is 0.600A. a. What is the current in the second wire ? b. Are the two currents in the same direction or in opposite direction?

Answer 1

a. The current in the second wire:

     $\frac{df}{dt}$= μ  $\frac{i_1 i_2}{2 * pi *r}$

⇒ $\frac{4 * 10^{-5}}{1} = \frac{2*10^{-7} * 0.06 * i_2}{2.5*0.01}$

⇒ $i_2 = 8.33 A$

B. Wires attract when currents are in same direction and repel when currents are in opposite direction. As the wires repel, currents are in opposite direction.

Answer 2

The current in the second wire is 8.33 A. The two current are in opposite direction.

Explanation:

Given data:

• Distance between wires = 2.50 cm = 2.5 x 10^-2 m
• Force = 4.00 x 10^-5 N/m
• Current in one wire = 0.600 A

Solution:

The formula is given below.

dF / dt = μo i1 i2 / 2 π r

4 x 10^-5  = 2 x 10^-7 (0.6) i2 / 2.5 x 10^-2

i 2 = 8.33 A

Hence the current in the second wire is 8.33 A

The two current are in opposite direction.