Physics quiz question: polarization by scattering

Physics 205B Quiz 1, spring semester 2013
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Multiple-Choice Question 22.6

If the sun is directly overhead, and you are looking at the south horizon, you would observe light that is:
(A) partially polarized horizontally, north-south.
(B) partially polarized horizontally, east-west.
(C) partially polarized vertically (up-down).
(D) randomly polarized (unpolarized).

Correct answer (highlight to unhide): (B)

Unpolarized light from the overhead sun, intercepted by an atmospheric particle at the south horizon, makes the particle vibrate horizontally north-south and vibrate horizontally east-west. From your viewpoint, you would only see the east-west horizontal polarization, as the north-south horizontal polarization would be longitudinal instead of transverse, thus the east-west horizontal polarization would dominate.

Section 30882
Exam code: quiz01b3Es
(A) : 5 students
(B) : 20 students
(C) : 9 students
(D) : 1 student

Success level: 57%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.72