# Force on a Magnet - Current Carrying Wire

1. May 14, 2014

### teme92

1. The problem statement, all variables and given/known data

A bar magnet, with pole strength 0.1 Wb and magnetic length (i.e. distance between the poles) of 5 cm, is placed so that one pole is 2 cm and the other 6 cm from a long, straight wire carrying a current of 6 Amps. The magnet lies in a plane perpendicular to the wire. Find the force on each pole of the magnet (indicating its direction on a diagram). What is the torque on the magnet about the axis of the wire

2. Relevant equations

F=qvB
F=BIl
B=$\mu$0I/2$\pi$R
$\phi$=BA

3. The attempt at a solution

So I said:

F=BIl and B=$\mu$0I/2$\pi$R, therefore:

F=$\mu$0I2l/2$\pi$R

In this formula is l the distance between the poles and R the distance the pole is from the wire? Any help would be much appreciated.

2. May 14, 2014

### Simon Bridge

Neither - afaict it's the wrong equation for the problem.
How do you determine the force on a magnetic pole due to a magnetic field?