The following animation shows what happens when a circularly polarized light wave traverses a light-absorbing medium (the refraction index is assumed to be 1, as before). We measure the field vector of the light before it enters and after it exits the medium, just like on the previous page.
The following animation shows the two intersecting planes from the front. On the left, before entering the material, on the right, after exiting the material.
As you can see, the intensity of light decreases exponentially inside the shown piece of material. After the light exits the medium, its field vector rotates as before but its length is only about 36% of the original value.