# Homework Help: Torque on a current carrying wire

1. Sep 27, 2011

### dimpledur

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

Consider the 20cm square loop of rigid wire shown in the figure. The wire has a diameter of 3mm and is lying flat on a table made of paramagnetic material. A uniform magnetic field of B=0.6 rans parallel to the table top as pictured. Electrical connection to the thick copper wire is established via two very thin, light leads as shown. The density of copper is 8.96g/cm^3 and the coefficient of friction is 0.2.
What value of current into the loop will cause the loop to start to move?
Describe how the loop will move.

2. Relevant equations

$\vec{F}=I(\vec{L}\times\vec{B}$

3. The attempt at a solution
I know that the force on the right hand leg will be directed out of the page, and that the force on the left leg will be into the page. As far as I can tell, the right side of the loop will want to lift off the table, and the left side will want to push into the table. I don't really think that friction will have a play in this. Would we merely apply sum of F=0 on the left leg?
mg=ILBsinx?

2. Sep 27, 2011

### sandy.bridge

The right hand side will begin to lift up, and eventually the force will have a component that opposes the frictional force. I don't know what else to do from here. Sorry