The following show electric field of polarized light.
$E_x(t)=E_{xo} cos(\omega t)$
$E_y(t)=E_{yo} cos(\omega t+\theta)$

You can use sliders to change $E_{xo},E_{yo}$ and $\theta$

If $E_{xo}=E_{yo}$ and $\theta=0$, it is a linear wave.
If $E_{xo}=E_{yo}$ and $\theta=\pi/2$, it is a circular polarized wave.
If $E_{xo}\ne E_{yo}$ it is an ellipse polarized wave.