Question

Two thin, long parallel wires separated by a distance ‘d’ carry a current of ‘i’ A in the same direction. They will

(1) attract each other with a force of μ₀i2/(2πd)
(2) repel each other with a force of μ₀i2 / (2πd)
(3) attract each other with a force of μ₀i2(2πd2)
(4) repel each other with a force of μ₀i2/(2πd2)

Answer 1

The correct answer is (1)
Using the definition of force per unit length due to two long parallel wires carrying currents.