PHYS2002 Spring 2012 Practice Exam 3 (Chs. 25, 26, 27) Constants

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1 PHYS00 Spring 01 Practice Exam 3 (Chs. 5, 6, 7) Constants m m q q p e ε = 8.85 o o p e = 1.67 = = = 1.60 μ = 4π k = 8.99 g = 9.8 m/s 1 kg C kg T m/a N m C / N m C / C

2 1. A convex mirror can form which of the following images: A) virtual, upright, reduced B) virtual, upright, enlarged C) real, inverted, reduced D) real, inverted, enlarged E) more than one of the other choices. or any single spherical mirror, a virtual image is: A) always inverted B) always upright C) sometimes upright and sometimes inverted D) None of the above 3. The figure below shows three laser beams with the same wavelength traveling in a liquid of unknown composition with index of refraction n. The beams strike a boundary with air, and Laser B is completely reflected back into the liquid as shown. Which statement best describes what happens to Lasers A and C? Laser A Laser B Laser B Laser C liquid A) A and C are totally internally reflected. B) Neither A nor C is totally internally reflected. C) A is totally internally reflected, but C is not. D) A is not totally internally reflected, but C is. E) A is totally internally reflected, but whether C is totally internally reflected depends on the value of n. air 4. An object (the arrow) is located to the left of a converging lens as shown below. The focal points of the lens are marked as. At what point A, B, C, D, or E is the image formed? Lens Object A B C D E

3 5. What could you do to improve the optical resolution of a microscope? A) Increase the wavelength of the light. B) Increase the diameter of the lens. C) Decrease the wavelength of the light. D) Both A and B. E) Both B and C. 6. A thin layer of oil floating on water will often appear multicolored. Which of the following processes explains why this happens? Choose the best answer. A) Reflection, refraction and diffraction B) Refraction, diffraction and polarization C) Refraction, diffraction and interference D) Reflection, refraction and interference E) Refraction, polarization and interference 7. A coin is placed 8.0 cm in front of a concave mirror. The mirror produces a real and inverted image that has a diameter 4.0 times larger than that of the coin. What is the image distance? A) 0.5 cm B).0 cm C) 6.4 cm D) 3 cm 8. When an object is placed 1 cm to the left of a lens, the image appears 6.0 cm to the left of the lens. What is the focal length of the lens? A) -4 cm B) +4 cm C) -8.3 cm D) -1 cm

4 9. You are looking down from above at a room that is 3 m 3 m square. A laser sits in the middle of the south wall and fires a beam of light that reflects off a plane mirror hanging on the east wall. Upon reflection, the beam then strikes a target located at the northwest corner (see figure). What is θ (the angle between the incident beam and the south wall)? A) 30 o B) 33.7 o C) 36.9 o D) 45 o Target 3.0 m North Wall East Wall West Wall 3.0 m Mirror Laser θ South Wall 1.5 m. Vertical light rays of red light (wavelength = 660 nm) and violet light (wavelength = 4 nm) are incident on a glass prism as shown. The indices of refraction in the glass for the red and violet light are and 1.703, respectively. The colors can emerge from the glass prism along possible paths. Which color(s) took Path 1? A) Red B) Violet C) Both colors took Path 1 D) Both colors took Path Red and Violet Light 90 o 90 o 8.0 o A light ray travelling in Material A strikes the interface with Material B at the Brewster s angle, which in this case is θ = 30. What would be the Brewster s angle for a light ray travelling in Material B and then striking the interface with Material A? A) 30 o B) 45 o C) 60 o D) 70 o E) There can t be a Brewster s angle for this situation. A B θ

5 1. I am farsighted, and the prescription on the box of my contact lenses says +.0 D. With my contacts on, I can read a book held 5 cm from my eye, but not any closer. How far away do I have to hold the book if I m not wearing my contacts? In other words, how far away is my nearpoint from my eye? A) 1.5 cm B) 5 cm C) 50 cm D) 0 cm E) None of the above 13. Doh. While jogging around the lake I accidentally drop my keys in the water. While looking for them I shine a light on the surface of the lake at an angle of 30 to the normal as shown. What s the angle of refraction of the light ray in the water? A) 15 B) C) 30 D) 4 E) o Water n=1.33 Air 14. An object (the arrow) is located to the left of a converging lens at a distance from the lens that is 40% of its focal length as shown in the figure below. What is the magnification and orientation of the image formed? A) m = (upright) B) m = (upright) C) m = (upright) D) m = (inverted) E) m = (inverted) Object 15. In a Young s double slit experiment, two slits with a separation distance of m create an interference pattern on a screen.3 m away. If the th bright fringe above the central bright fringe is located 1 cm above it, what is the wavelength of the light being used in the experiment? eel free to use the small angle approximation: sinθ tanθ. A) 49 nm B) 440 nm C) 850 nm D) 90 nm E) None of these.

6 16. A beam of blue light (λ vacuum = 465 nm) strikes a thin film of soap of thickness t resting on a diamond surface (see figure). The indices of refraction for air, soap, and diamond are 1.00, 1.33, and.4, respectively. What is the smallest nonzero thickness for the soap film, such that it appears dark? eye A) 87 nm B) 116 nm C) 350 nm D) 465 nm t n air = 1.00 n soap = 1.33 n diamond = In low light, a cat s pupils, which are slit-shaped in bright light, open to a large circular diameter of about 1 mm. How close (r) would my cat Socola have to be in order to just resolve two mice separated by a distance of 5 cm? Assume Socola is watching the mice in red light, which has a wavelength of 630 nm in his eye. A) m B) m C) 78 m D) 780 m r r 5 cm