Chapter 22, Problem 38PE

(a) A 0.750-m-long section of cable carrying current to a car starter motor makes an angle at 60° with the Earth’s $5.00\times {10}^{-5}\text{-T}$ field. What is the current when the wire experiences a force of $7.00\times {10}^{-3}\text{N}$ ? (b) If you run the wire between the poles of a strong horseshoe magnet, subjecting 5.00 cm of it to a 1.75−T field, what force is exerted on this segment of wire?