Does light intensity change with two polarizing sheets?

[jdroidxw]

Homework Statement

Unpolarized light of intensity Io is incident on two polarizing sheets whose axes are perpendicular.
A) what is the intensity of the light after the first sheet?
B) what is the intensity of the light after the second sheet?

Homework Equations

I=(Imax)cos^2(Θ)

The Attempt at a Solution

A) I thought the intensity would not change since you need two polarizing sheets at certain angles to change the intensity.

B) Intensity is 0? If I plug 90° into the relevant equation, I=0 since cosine at 90 degrees is zero.

Would I be correct in my steps?

 

[TheAustrian]

Yeah, two linear polarizers tilted at 90 degrees relative to each other will absolutely (or nearly absolutely) block all light from reaching the observer at the other end.

 

[jdroidxw]

Okay thank you! And what about the one sheet? Would I be correct in saying that it would not have any effect regardless of the angle?

 

[TheAustrian]

There would be some reduction in intensity with one polarizer.

 

[HalfLostAndSearching]

I would say that your steps are correct. The intensity of light does not change when passing through a single polarizing sheet. However, when two polarizing sheets are placed with their axes perpendicular to each other, the intensity of light passing through will be reduced to zero. This is because the second polarizing sheet blocks all the remaining polarized light from the first sheet, resulting in a complete blockage of light. This phenomenon is known as crossed polarization and is commonly used in polarizing filters in photography and other applications.