Unpolarized light of intensity I_0 is incident on a polarizer. The transmitted light is then incident on a second polarizer. The axis of the second polarizer makes and angle of 60 degrees to the axis of the first polarizer. Calculate the fraction of intensity transmitted.

I used the formula I = I_0*cos²(x)
x=60
I = I_0*cos²(60) = I_0 * 1/4

However the book says I_0 * 1/8

What am I doing wrong?

Question

Unpolarized light of intensity I_0 is incident on a polarizer. The transmitted light is then incident on a second polarizer. The axis of the second polarizer makes and angle of 60 degrees to the axis of the first polarizer. Calculate the fraction of intensity transmitted.

I used the formula I = I_0*cos²(x)
x=60
I = I_0*cos²(60) = I_0 * 1/4

However the book says I_0 * 1/8

What am I doing wrong?

anonymous · Answer

first polariser will alredy reduce it I_0 by 1/2 ..then afterwards second will reduce I_0/2 by 1/4 to give I_0/8..

anonymous · Answer

Oh, that makes sense. Thank you :)