# Magnetic force b/w wires of unequal length

1. May 17, 2010

### diagopod

Is there a formula for the force between two parallel wires of non-equal length? Would one just use the length of the shorter of the two wires?

2. May 17, 2010

### clem

That would only work if the longer wire were very much longer.
You can get the field of the longer, but finite, wire by the usual Biot-Savart integral with finite limits. Then integrate this field over the shorter wire.

3. May 17, 2010

### diagopod

Thanks, that does makes sense.