# Distance dependence in Ampere's force law

1. Jan 24, 2013

### Sunfire

Hello,

In the Ampere's force law

F=2ka$\frac{I_{1}I_{2}}{r}$

Ampere law,

the force between 2 parallel conductors doesn't seem to depend on the distance between them.

F is given in [N/m], instead of just [N]...

What is the rationale behind this?

Thank you.

2. Jan 24, 2013

### Sunfire

Does it stem from the definition of Ampere

3. Jan 24, 2013

### Sunfire

Reading some other threads on the subject helps... I see that the force is per unit of cable length, while r on the RHS is the distance betw the 2 cables, okay :)

4. Jan 24, 2013