In Fig. 3-1, unpolarized light is sent into a system of three polarizing sheets.
ID: 1775081 • Letter: I
Question
In Fig. 3-1, 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 ofthe y axis (they are not drawn to scale). Angles 1 and 3 are fixed, but angle 2 can be aried. Figure 2 gives the intensity of the light emerging fronm sheet 3 as a function of 2. (1 he scale of the intensity axis is not indicated.) What percentage of the light's initial intensity is transmitted by the system when 2-45? 82 0 82 0° 90° 180° Figure 3-1 Figure 3-2Explanation / Answer
Initial light(I0) before 1st polarizer is un-polarized
Hence intensity after 1st sheet = I1=1/2*I0 = I0/2 -------------(1)
So maximum intensity of the light emerging from the 3rd sheet can be = I0/2
Where I0 = Intensity of initial un-polarized light before 1st sheet
The graph shows when 2=45 deg , intensity of the light emerging from the 3rd sheet is maximu,
Thus,
Intensity after 3rd sheet = I3= I0/2
Ratio of the light transmitted by system to the initial intensity is as below,
The light transmitted by system/ The initial intensity = (I0/2)/I0 = 1/2
Thus percentage = ½*100 = 50%