# Polaroid (conceptual doubt)

#### Suyash Singh

1. Homework Statement
It is just a conceptual doubt

2. Homework 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)

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#### gneill

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

Thankyou :)