Finding Incident Intensity for Unpolarized Light


by wiped_out
Tags: incident, intensity, light, unpolarized
wiped_out
wiped_out is offline
#1
Sep8-09, 02:46 AM
P: 2
1. The problem statement, all variables and given/known data
Two sheets of Polaroid are placed on top of each other with an angle φ between their pass
directions. Calculate be the ratio of transmitted to incident intensity for initially unpolarised
light if φ = 30.


I copied the question exactly, I'm pretty sure that typo wasn't on purpose but I left it there anyway.

2. Relevant equations

I0 = I'/2

Malus's Law
I = I0 cos^2 θ

3. The attempt at a solution

I used the equation above to do:

= I0 cos^2(30)
cos^2(30)=.75
.75 x .75 = .5625 = 9/16
= I0(9/16)

not sure if that is right
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rl.bhat
rl.bhat is offline
#2
Sep8-09, 05:35 AM
HW Helper
P: 4,442
When the unpolarised light is transmitted through a Polaroid, 50% of light is transmitted. So I' = Io/2
When it passes through second Polaroid, the intensity of transmitted light is
I" = Io/2*cos^2(θ)


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