Question

A square loop of wire 0.3 meter on a side carries a current of 2 amperes and is located in a uniform 0.05-tesla magnetic field. The left side of the loop is aligned along and attached to a fixed axis. When the plane of the loop is parallel to the magnetic field in the position shown, what is the magnitude of the torque exerted on the loop about the axis?

A) 0.00225 Nm

B) 0.0090 Nm

C) 0.278 Nm

D) 1.11 Nm

E) 111 Nm

Answer 1

The correct option is: B) 0.0090 Nm

Explanation:

Based on the axis given. The left side wire is on the axis and makes no torque. The top and bottom wires essentially cancel each other out due to opposite direction forces, so the torque can be found from the right wire only. Finding the force on the right wire … Fb = BIL = (0.05)(2)(0.3) = .03 N, then torque = Fr = (0.03)(0.3).