Chapter 22, Problem 41PCE

A square loop of wire 0.15 m on a side lies on a horizontal table and carries a counterclockwise current of 4.2 A. The component of Earth’s magnetic field that is in the plane of the loop is 2.5 × 10⁻⁵ T and points toward the top of the loop. (a) Consider a horizontal axis of rotation that passes through the center of the loop from left to right. Does the top wire of the loop want to rotate toward you (up from the table) or away from you (down into the table)? (b) Calculate the magnitude of the torque about the axis described in (a).