How Is Torque Calculated on a Rectangular Coil in a Magnetic Field?

[coffeem]

Homework Statement

A rectangular coil consists of 25 turns of wire forming a square 4cm each side. By considering the force on a current-carrying straight wire, calculate the torque acting on the coil when the normal is at 30 degrees to a magnetic field of 0.8T and 12 A are flowing.

Homework Equations

t = ucrossB

F = IlcrossB

The Attempt at a Solution

Umm I am a bit stuck with this as I do now know why I am meant to be using the force acting on the current carrying wire. I thought I could just use the t = ucrossB formula in the form:

t = ubsintheta

where u = IA

However this clearly isn't correct so I am looking for some help! Thanks

 

[rl.bhat]

Torque τ = ΝΒΙΑsin(θ)