Describing electromagnetic radiation, why is there a second sin term?

[daselocution]

Homework Statement

Hey all,
I am working through a derivation that my professor gave me to do and I am having trouble understanding one of the formulas that he gave me, namely:

"EM waves can be described as:
E(x, t) = E_osin(2πx/λ)*sin(2πc/λ)"

The the E_o*sin(2πx/λ) term makes sense to me. I am wondering why there is a second sin term (the sin(2πc/λ)) term in the equation. I understand that c/λ = f, but in that case I still don't really understand why this term is in here. Is there a source that derives this equation anywhere? I am having trouble finding a way to understand this equation.


 

[tiny-tim]

hi daselocution!

E_osin(2πx/λ)*sin(2πc/λ)

shouldn't there be a t in there somewhere?