# Magnetic Force

1. Apr 26, 2005

### leolaw

Ok, this problem shows up on my test today and I was wondering how you can solve it:

A circular coil of wire has a diameter of 20 cm and contains 10 loops, internal resistance of 8 ohms, and the coil is placed in a 2.00T external magnetic field. When 1 volt is applied to the coil, determine the maximum force exerted on the coil by the field.

First of all, I was thinking about using $$R = \rho \frac{l}{A}$$ and plug in the $$l$$ into $$F = IlB sin \theta$$
But I wasnt given the $$\rho$$, so i try the torque formula:$$NIABsin\theta$$, but end up having Netwon * meter for the unit

How should i approach this problem?

2. Apr 27, 2005

### OlderDan

The resistance of the wire is given as 8 ohms. The applied potential is 1 volt. The current is a simple calculation based on this information. After you get that, your appraoch to the magnetism aspects looks reasonable.

3. Apr 27, 2005

### leolaw

But how can i solve for $$l$$ in order to calculate the Force by using $$F = I l B sin \theta$$ ?