Calculating Electric Field Amplitude of Transmitted Light

[sheepcountme]

Homework Statement

A beam of unpolarized light with intensity 30 watts/m^2 passes through a polarizing sheet. What is the electric field amplitude of the transmitted beam?

Homework Equations

Ia=Ipcos²$$\Theta$$
Ea=Epcos$$\Theta$$
Ip=Io/2

The Attempt at a Solution

I solved the first two equations for cos$$\Theta$$ and set them equal to each other to get sqrt(Ia/Ip)=Ea/Ep

I know Io is 30, so Ip is 15

So then, I believe I should have sqrt(2)=Ea/Ep and I don't know how to just solve for one without the other...

 

[ehild]

you need to know how the intensity of light is related to the electric field intensity. Look after in your textbook.

ehild

 

[sheepcountme]

Ah, okay, so scrap all that and use I=(E²)/$$mu$$oc

Thanks!

The book apparently likes to put questions at the end of random chapters!