# Definition of unit of electric current

1. Jun 30, 2010

### Quantumkid

The ampere is that constant current which , if maintained in two straight parallel
conductors of infinite length, of negligible
circular cross-section
, and placed 1 metre apart in vacuum, would produce between
these conductors a force equal to 2 × 10 ^{–7} newton per metre of length.

What is meant by orange colored text??

2. Jun 30, 2010

### mgb_phys

Yes - and your question is ?

3. Jun 30, 2010

### DrDu

It means that one considers the limit that the wires are infinitely thin.