Question

If the perpendicular distance d between two parallel current-carrying conductors is doubled, the force per unit length F/L:

Options

• Remains unchanged

• Is halved, because of inverse proportionality to d

• Doubles, because of direct proportionality to d

• Becomes one-fourth of its original value

Answer 1

Since F/L = μ₀IaIb/(2πd), the force per unit length is inversely proportional to the perpendicular distance d. Doubling d halves F/L.