In Figure (a) below, unpolarized light is sent into a system of three polarizing
ID: 1906762 • Letter: I
Question
In Figure (a) below, unpolarized light is sent into a system of three polarizing sheets.The angles ?1, ?2, and ?3 of the polarizing directions are measured counterclockwise from the positive direction of the y axis (they are not drawn to scale). Angles ?1 and ?3 are fixed, but angle ?2 can be varied. Figure (b) gives the intensity of the light emerging from sheet 3 as a function of ?2. (The scale of the intensity axis is not indicated.) What percentage of the light's initial intensity is transmitted by the three-sheet system when ?2 = 124o?
Explanation / Answer
You need to calculate the effect of each polarizing sheet separately. The first sheet reduces the intensity by 50% as it filiters out one component of the unpolarized light. Use your formula to find the intensity transmitted by the second sheet I(cos(14°)^2) = 94% The third sheet has exactly the same effect as the second sheet, as its angle difference is also 14°. The transmission of the system is the product of the individual transmissions, because the second sheet transmits 94% OF the 50% transmitted by the first sheet, etc., and then the third sheet transmits 94% of whatever the second sheet transmits.