# Current required in a long wire

1. Feb 3, 2015

### rwilson5

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

Determine the amplitude of a magnetic field in an electromagnetic wave that carries a flux density of 100 mW/cm2. How much current would be required in a long straight wire so that the magnetic field if this same amplitude would be generated at a distance of 1mm from the wire.

2. Relevant equations

$$B_0=\frac{E_0}{c}=\frac{1}{c}\sqrt{\frac{2I}{c\epsilon_0}}$$

3. The attempt at a solution

I'm not sure how to get at this one. I got that $$B_0=2.89 \cdot 10^{-6} T.$$ Just a touch in the right direction would be awesome.

2. Feb 3, 2015

### Staff: Mentor

The approach looks fine, and a computer can check the numerical value. Where is the problem?