Magnitude of magnetic torque on a current loop (19-8)

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Question

Area of the loop
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Review

Although we’ve assumed a rectangular loop, Equation 19-8 applies to a current loop of area \(A\) of any shape.

Typically, the rotating coil in an electric motor is not just a single loop of wire, but has many turns (equivalent to many single coils stacked on top of each other). If a coil has \(N\) turns, the magnetic torque on it is \(N\) times greater than the value given by Equation 19-8.