# Homework Help: ELECTROMAGNETISM-torque on a current coil

1. Aug 30, 2009

### jsalapide

A circular coil of 50 turns has a radius of 0.2m and carries a current of 5A. The coil is in a field where the magnetic induction is 0.6 Web/m^2. What is the max torque on the coil?

I used the formula for the torque on a coil: r=NBIAcos(theta)
I assume that the angle for max torque is 0

is that right?
is it ok to let the angle be 0??

2. Aug 30, 2009

### Staff: Mentor

Looks OK to me.

I'm not sure how you defined your angle theta. Usually it's defined as the angle between the area vector (normal to the plane of the coil) and the magnetic field, in which case the torque is given by μ X B = NIAB sin(theta). Using that definition, the torque is maximum when theta = 90 degrees.

3. Aug 30, 2009

### jsalapide

Ah.. my theta is the angle between the plane of the coil and the field

anyways,, thanks..

how about the unit? Is it web-A?

4. Aug 30, 2009

### Staff: Mentor

The standard unit for torque is Newton-meter (which is equivalent to web-A).