PHY 102 Quiz #7 Name ______

Score _____ Instructions: 1. Do all of your work on this sheet. 2. Show all of your steps in problems for full credit. 3. Problems (13 pts) 3. Be clear and neat in your work. Any illegible work, or a. Unpolarized light with intensity 3.0 W/m2 strikes a piece scribbling in the margins, will not be graded. of polarizing material. It passes through and comes into 4. Place your answers in a box. contact with another polarizing material, which is at 30o 5. If you need more space, you may use the back of the with respect to the first. What is light intensity that is page and write On back in the problem space. transmitted through these polarizing materials? ______1. Multiple Guess (3 pts) Find the answer which best fits the question and write it in the space provided. a. Which is not a consequence of Einstein's postulates? a) Moving clocks tick slower than stationary ones.. b) Simultaneous events in one inertial system may not be b. A thin film of an anti-reflective coating (n = 1.30) coats a simultaneous in another system. thin lens (n = 1.69). What is the minimum thickness of c) Stationary lengths are smaller than moving lengths. the d) None of these. film if 530 nm wavelength light is not reflected? _____ b Suppose you are using a microscope to view two closely spaced cells. For a given lens diameter, which color of light would you use to achieve the best possible resolving power? a) Red b) Yellow c) Green d) Blue e) All the colors give the same resolution. _____ c. What is the energy equivalent of a 0.75 g mass? Compare c. A spaceship moves towards you at 1/3c, where c is the this to the 15 kilotons of TNT released by the Little Boy speed of light. The spaceship emits a beam of light in bomb where one kiloton (kT) = 4.186 1012 J. your direction. As measured in your frame of reference, the speed of the light emitted by the spaceship is: a) 4/3c. b) c. c) 2/3c. d) 1/3c. _____

2. Definition/Principle (4 pts) a. What is Huygen’s Principle?

d. Over a five minute period an Earth observer measures a b. What is an inertial reference frame? spaceship traveling towards him at 0.50c as 650 m long. i. How much time passes on the spaceship?

ii. What is the length of the spaceship after it lands?

e. Light of wavelength 430.0 nm is incident on a single slit of Bonus: In the original Planet of the Apes movie, Taylor and width 1.8 10-4 m. How far is the second minimum from his crew traveled for 18 months only to find that the time on the center of the diffraction pattern on a wall 1.50 m from Earth changed by 2000 years. If they had traveled at a the slit? constant speed, how fast were they moving? PHY 102 Quiz #7 Name ______

Score _____