Question

(Physics Lab, can you explain clearly for me, please?)

1. Taking a polarizing filter outside the classroom and look through the filter at the blue sky. Look in a direction perpendicular to the direction of the sun's rays/ Slowly rotate the filter as you look through it noting the direction of the filter's TA. What do you observe? Explain and discuss.

2. Now take the same filter and look at the sunlight reflecting off a smooth, non-metallic surface (such as the car glass). Follow the same procedure before, explain your observations.

Answer 1

1) You would observe that for a particular angle of rotation for the polarizer, the light through the filter will be minimum. This is because what you are observing is the light reflected or rather scattered by the air molecules. This scattering of light makes the light partially polarized (which is why only one polarizer was needed and not two).

2) Similar to above, the light intensity through the polarizer will fall to a minimum at a particular angle. However, the reason here is not scattering but rather reflection of light at Brewster's angle. For a given angle where , the reflected light will be linearly polarized. So when you observe the reflected sunlight, some of it is incident at Brewster's making the reflected light linearly polarized.