# Homework Help: Polaroid (conceptual doubt)

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1. Dec 31, 2017

### Suyash Singh

1. The problem statement, all variables and given/known data
It is just a conceptual doubt

2. Relevant equations
According to malus law intensity of light through polaroid is
I=(Io)cos^2(theta) where theta is the angle between axis of polaroid and incident light.

3. The attempt at a solution
But when Theta=0 then I=Io but in my book it is I=Io/2.
why??

and also is my diagram below correct?

--->(light)(I) [](polaroid) --->(I/2) [] --->(I/4) (theta=0 degrees for both polaroid)

2. Dec 31, 2017

### Staff: Mentor

$I_o$ is generally taken to be the intensity of the light after an unpolarized source has passed through one polarizer (hence polarizing it). Half of intensity of the source is lost by the first polarization.

Take a look at the diagram for the Law of Malus entry on the Hyperphysics web site:

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polcross.html#c1

3. Jan 4, 2018

Thankyou :)