Question

GOAL Understand how polarizing materials affect light intensity. Unpolarized light is incident upon three polarizers. The first polarizer has a vertical transmission axis, the second has a transmission axis rotated 30.0 degree with respect to the first, and the third has a transmission axis rotated 75.0 degree relative to the first. If the initial light intensity of the beam is I_b, calculate the light intensity after the beam passes through the second polarizer and the third polarizer. After the beam passes through the first polarizer, it is polarized and its intensity is cut in half. Malus's law can then be applied to the second and third polarizers. The angle used in Malus's law must be relative to the immediately preceding transmission axis. Calculate the intensity of the beam after it passes through the second polarizer. The incident intensity is I_b/2. Apply Malus's law to the second polarizer. I_2 = I_0 cos^2 theta = I_b/2 cos^2 30 degree = I_b/2 ((3)^1/2/2)^2 Calculate the intensity of the beam after it passes through the third polarizer. The incident intensity is now 3 I_b/8. Apply Malus's law to the third polarizer. I_3 = I_2 cos^2 theta = 3 I_b/8 co^2 45 degree = 3 I_b/8 ((2)^1/2/2)^2 Notice that the angle used in part (b) was not 75.0 degree, but 75.0 degree - 30.0 degree = 45.0 degree. The angle is always with respect to the previous polarizer's transmission axis because the polarizing material physically determines what direction the transmitted electric fields can have. At what angle relative to the previous polarizer must an additional polarizer be placed so as to completely block the light? The polarizers are rotated so that the second polarizer has a transmission of 39.6 degree with respect to the first polarizer and the third polarizer has an angle of 90.0 degree with respect to the first. If I_b is the intensity of the original unpolarized light, what is the intensity of the beam at the following times. after it passing through the second polarizer after it passing through the third polarizer What is the final transmitted intensity if the second polarizer is removed?

Answer 1

J. 0.122