# Speed of light question

1. Dec 19, 2006

### dt19

this isn't actually homework but i fear it is too simple to put in any of the other forums
why is it that you can calculate the speed of light by (permettivity*permeability of free space)^-0.5
i can't seem to find it in any of my textbooks, but my physics teacher told me it was a standard proof thing...

2. Dec 19, 2006

### stunner5000pt

you can derive it using maxwell's equations

3. Dec 19, 2006

### Staff: Mentor

More specifically, if you use Maxwell's equations to derive the wave equation for E or B, you get something that looks just like the standard differential wave equation, with $1/\sqrt{\epsilon_0 \mu_0}$ where the wave speed should be.

4. Dec 19, 2006

### dt19

is it something doable by an A level student? cos i've heard about maxwell's equations but it's not on the syllabus...
also, what are E and B?

5. Dec 19, 2006

### stunner5000pt

E = electric field
B = magnetic field

how much calculus have you done??

6. Dec 19, 2006

### dt19

int. by parts, substitution, integrating trig, first order differential equations

7. Dec 19, 2006

### Staff: Mentor

Sounds like you have a lot of the background, as long as you've had some vectors mixed in with the calculus. I googled something like maxwell equations derivation wave equation, and got lots of good hits. Here's one of the first hits on the list:

http://www.mathphysics.com/pde/Maxwell.html

EDIT -- Also, if you have access to a technical library, just check out some of the books on Electromagnetics. Most will have the derivation.