# Relating B and E in an electromagnetic wave

## Homework Statement

I need to determine B(rms) in terms of E(max) given a standard E-M wave.

E = cB

## The Attempt at a Solution

I assumed that B(max) is sqrt(2) x B(rms) and then just plugged in for B(max) in the equation above. Am I right in assuming the rms value involves a square root? (I get confused if it's 2 or sqrt(2))