A straight, long wire carries an electric current of 20 A. Another wire carrying same current is kept parallel to it. If force acting on a length of 10 cm of the second wire is 2.0 × 10–5 N, what is the distance between them?

Current on both wires i1=i2=20A


Force acting on 10 cm of the second wire, F =20 x 10-5


∴ force per unit length =


Now, let the distance between the two wires be d. Thus, the force per unit length is given as:



⇒


⇒ distance d = 0.4m =40cm


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