In the figure the orientation of the transmission axis for e

In the figure, the orientation of the transmission axis for each of three polarizing sheets is labeled relative to the vertical direction. A beam of light, polarized in the vertical direction, is incident on the first polarized with an intensity of 1000 W/m^2. What is the intensity of the beam after it has passed through the three polarizing sheets when theta_1 = 30degree, theta_2 = 30degree and theta_3 =60degree?

Solution

Intensity of the polarized light I = 1000 W/m ²

Intensity of the light after passed through first polarizer I \' = I cos ² 30

     I \' = 1000 (0.75 ) = 750 W/m ²

Intensity of the light after passed through second polarizer I \" = I \' cos ² (30-30)

I \" = 750 (1)

     = 750 W/m ²

Intensity of the light after passed through third polarizer I\"\' = I\" cos ² ( 60 -30 )

             I\"\' = 750 cos ² 30

                = 750 (0.75)

                = 562.5 W/m ²