Two long parallel wires are separated by 4.0 cm. One of the wires carries a current of 20 A and the other carries a 30-A current. Determine the magnitude of the magnetic force on a 2.0-m length of the wire carrying the greater current.
A) 7.0 mN
B) 6.0 mN
C) 8.0 mN
D) 9.0 mN
E) 4.0 mN

Question

Quizplus · Accepted Answer

The magnetic force per unit length between two parallel currents is given by $ F/L = \frac{\mu_0 I_1 I_2}{2\pi d} $. Substituting $ \mu_0 = 4\pi \times 10^{-7} \, \text{T}\cdot\text{m/A} $, $ I_1 = 20 \, \text{A} $, $ I_2 = 30 \, \text{A} $, $ d = 0.04 \, \text{m} $, and $ L = 2.0 \, \text{m} $, the force is $ F = 6.0 \, \text{mN} $.

Two Long Parallel Wires Are Separated by 4