You have a circular loop of current carrying wire in a large uni-form magnetic field. Because it's a current carrying loop in a magnetic field, there will be a torque acting on it. Your friend wants to increase the torque by doubling the loop over on itself, so that it now makes two circular loops on top of each other by using the same length of wire. What is the new torque in terms of the old torque?

Answer: Torque (τ) = NIABsinθ

Explanation:

Motors have loops of wire in a magnetic field. When current is passed through the loops, the magnetic field exerts torque on the loops, which rotates a shaft.

If we have a multiple loop of N turns, we get N times the torque of one loop. Finally, note that the area of the loop is A = wl; the expression becomes

Torque (τ) = NIABsinθ

Where N = number of turn of the loop

I = current

A = area

B = magnetic field.