Question

A vertical straight wire carrying an upward 29 A current exerts an attractive force per unit length of 7.1×10−4 N/m on a second parallel wire 7.5 cm away.

What current (magnitude and direction) flows in the second wire?

Answer 1

We are using the formula for this particular question as shown in image-

Where   = 4 x 10^{- 7} T m/A.

Than as per the question-

7.1 * 10^-4 = ( 4 x 10^{- 7} ) (29 * I₂) / (2 * 7.5 *10^-2)

7.1 * 10^-4 = ( 58 x 10^{- 5} ) *  (I₂) / 7.5

I₂ = (7.1*7.5) * 10 / 58

I₂ = 9.18 A

For diretion, go with uploaded image-

Direction in wire 2 will bw upward.

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