Question

Unpolarized wave, $\Delta\varphi =\Delta \varphi(t)$?

Answer 1

I have seen a unpolarized wave defined in a number of places (e.g. here) as a wave such that:

ExEy=E0cos(kz−ωt)=E0cos(kz−ωt+φ)Ex=E0cos⁡(kz−ωt)Ey=E0cos⁡(kz−ωt+φ)

Where φ=φ(t)φ=φ(t) is a random function in time. 
My question is why do we not have φ=φ(x,y,z,t)φ=φ(x,y,z,t) with it been a random function in time and space

Answer 2

Hey mate....

here's the answer.....

ExEy=E0cos(kz−ωt)=E0cos(kz−ωt+φ)Ex=E0cos⁡(kz−ωt)Ey=E0cos⁡(kz−ωt+φ)

Where φ=φ(t)φ=φ(t) is a random function in time. 

My question is why do we not have φ=φ(x,y,z,t)φ=φ(x,y,z,t) with it been a random function in time and space...

Hope this helps❤️