A current I flows in a plane rectangular current loop with height w and horizontal sides b. The loop is placed into a uniform magnetic field B⃗  in such a way that the sides of length w are perpendicular to B⃗  (Figure 1) , and there is an angle θ between the sides of length b and B⃗  (Figure 2) .Calculate τ, the magnitude of the torque about the vertical axis of the current loop due to the interaction of the current through the loop with the magnetic field.

Express the magnitude of the torque in terms of the given variables. You will need a trigonomeric function [e.g., sin(θ) or cos(θ)]. Use B for the magnitude of the magnetic field.

  

(current coming up) B. (current going down) View from above