Originally, light is unpolarized. It then travels through 3 polarizers: the first with its transmission axis aligned vertical, the next at a 30 degree angle to the vertical and the last aligned at a 45 degree angle to the vertical (tilted the same direction as the first with respect to the vertical). The original intensity of light is 4 W/m2. What is the intensity of the light after the first polarizer? second polarizer? third polarizer? If the second polarizer is aligned at a 45 degree angle to the vertical (just like the third). what is the final intensity of light after the third polarizer? If the second polarizer is aligned at a 45 degree angle to the vertical (but in the other direction), what is the final intensity of light after the third polarizer?
Explanation / Answer
Original intensity of light I = 4 W/m 2 (1).Intensity of the light after first polarizer I ' = I/2 = 2 W/m 2 (2).Intensity of the light after second polarizer I" = I ' cos 2 45 = 1 W/m 2 Final intensity of the light after third polarizer I "' = I" cos ( 45-45) = I" = 1 W/m 2 (3).Intensity of the light after second polarizer I" = I ' cos 2 45 = 1 W/m 2 = 1 W/m 2 Final intensity of the light after third polarizer I "' = I" cos ( 45+45) = 0 Since cos 90 = 0