Please show all work, thanks! 9) Unpolarized light, with intensity I 0 , travels

Question

Please show all work, thanks!

9) Unpolarized light, with intensity I0, travels through a horizontal polarizer.

a) What is the intensity of the light after the first polarizer?

b) A vertical polarizer is placed after the first polarizer, what is the intensity of light emerging from the second polarizer?

c) A third polarizer, with polarization 40o from the horizontal, is placed between the horizontal and vertical polarizers. What is the intensity of light after it passes through all three? [Answer: 0.50 I0, 0.29 Io, 0.12 Io]

Explanation / Answer

Intensity I of polarizer is goverened by malus law as

I = Io cos^2 theta

partA:

after passing through first polarizer, Intensity I falls by 50 %

so

I1 = Io/2

-----------------------------------

I = Io/2 cos(40) = I

I2 = Io./2 * cos ^2 ( 40)

I2 = Io/2 * 0.707*0.707

I2 = 0.29 Io

-----------------------
again when theta = 90-40 deg = 50 deg

I3    = 0.29 Io cos^2(50)

I3 = 0.12 Io

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