# Unpolrized light passes through 2 polarizers

## Homework Statement

Unpolarized light passes through two polarizers whose transmission axes are at an angle of 28.1° with respect to each other. What fraction of the incident intensity is transmitted through the polarizers?

## Homework Equations

I=.5xIoxcos^2(theta)

## The Attempt at a Solution

Im pretty sure that i have the correct equation, but i'm confused because in the problem I am not given an Incident Intensity, therefore how can i solve for the transmitted intensity? If someone could please start me in the right direction, i would appreciate it very much!

alphysicist
Homework Helper
Hi Cheezay,

## Homework Statement

Unpolarized light passes through two polarizers whose transmission axes are at an angle of 28.1° with respect to each other. What fraction of the incident intensity is transmitted through the polarizers?

## Homework Equations

I=.5xIoxcos^2(theta)

## The Attempt at a Solution

Im pretty sure that i have the correct equation, but i'm confused because in the problem I am not given an Incident Intensity, therefore how can i solve for the transmitted intensity?
They are not asking for the transmitted intensity, they are asking for the fraction of the incident intensity that is transmitted, which is the ratio of transmitted intensity to incident intensity. Do you see how to solve for that?

No, i'm sorry i don't see how to solve for that. I thought maybe it might be 1/2 the incident intensity, but that answer is not correct.

alphysicist
Homework Helper
No, i'm sorry i don't see how to solve for that. I thought maybe it might be 1/2 the incident intensity, but that answer is not correct.

The ratio you're looking for is:

(transmitted intensity) / (incident intensity) = I / Io

Using your equation (from your first post), what is that quantity equal to?

Then I/Io= .5 x cos^2(theta). Thanks so much for the help!