Question

If the current I_a in conductor a is doubled while I_b and the distance d remain unchanged, the force per unit length F/L between the conductors:

Options

• Becomes four times larger

• Is halved, because of inverse proportionality to I_a

• Doubles, because of direct proportionality to I_a

• Remains unchanged

Answer 1

Since F/L = μ₀I_aI_b/(2πd), the force per unit length is directly proportional to each current. Doubling Ia doubles F/L.