Question

Unpolarized light of intensity of 40 W/m2 passes through three polarizers as drawn below. Find the intensity and polarization direction (angle from the y- axis). a) At position a. b) At position c. х Io = 400 g TA. TA T.A. с

Answer 1

P2 12 an The above experiment can be as easily understood by assuming that light passing through the polaroid P2 gets polarised along the bass-axis of P. If the pass anis of P2 makes angle o with the per pass-axis of P., then when the polarised beam passes through the polaroid P2, the Component Ecoso (along the pars-anis of P2) will pass through P2. Thus, rotate the polaroid P (or P2), the intensity will vazy as where o in angle between pars-anin of two polaroids. we I =I, Conze بیا

Now, in our given question, we have 0=30°, and I=40 W m2 Angle O, in between P, and P₂ is 60° P VI, thus, I = I Cos²o 690° Angle Oz inbetween P₂ & B is 60°. P2 Y I,= 40 Con230 IC b = 40. (132)= 10x3 30° = I= 30 W/m² at an angle of 30° from Y-direction. P3 Iz Yc Now, Iz = I, cos260° = 30. (/)2 30 at an angle of 90° from Y-direction.

Now, Iz= Iz Cos²O₂ = 30 30. Cos? 60 Cos² 60° = 30 Is = 30 16 W/m2 at an angle of 30° from Y-direction Thus, (a) Intensity and polarization direction at position 'a is I,= 30 W/m² at angle 35 (6) Intensity and polarization direction at position 'c' is Iz= 30 = 1.875 W/m2 at angle 30° from Y-direction.