Spring 09 Final Exam

E136ev34evand15 evabeamofphotonsofawiderangeofenerg

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Unformatted text preview: am of electrons e. either a beam of electrons or a beam of neutrons f. any of these: a beam or photons, a beam of electrons, or a beam of neutrons g. none of the above (15‐17) 15. (2 pts) Light of a single wavelength shines on a metal which has a work function of 2.0 eV. The maximum kinetic energy of emitted electrons is determined to be 3.0 eV. The energy of the incident photons is a. 5.0 eV b. 3.0 eV c. 2.0 eV d. 1.0 eV 16. (2 pts) Now the light that shines on this metal is changed, and it’s observed that no electrons are emitted. What change in the light could account for this? a. the intensity has increased b. the intensity had decreased c. the wavelength has increased d. the wavelength has decreased 17. (2 pts) Going back to the original light, we now replace the metal with one that has a slightly greater work function. We would expect the maximum kinetic energy of the emitted electrons to be a. greater b. less c. the same 18. The diagram shows an edge‐on view of a circular loop of wire carrying a current. (Each of the four larger circles represents a magnetic compass.) At the center of the loop, the magnetic field due to the current‐carrying loop is directed up. a. Indicate the direction of the current in the loop. (2 pts) b. On each compass, indicate with an arrow the direction that the north pole of the compass needle points. (2 pts) Name__________________________________ 19. The graph below represents two pulses traveling in opposite directions at 1.0 m/s. On the axes at right, show the superposition of the two waves at t = 2.0 s. (2 pts) 20. From the graph at right, and the knowledge that the speed of the wave is 2.0 cm/s, determine the following: a. the amplitude of the wave (2 pts) b. the wavelength of the wave (2 pts) c. the frequency of the wave (3 pts) 21. The ray diagram below shows the path of two light rays from the top of an object through a lens. a. Indicate on the diagram the location of the image formed by the lens. (2 pts) b. Is the image upright or inverted? (1 pt) c. Is it possible to view the image formed by the lens on a screen? If so, indicate on the diagram where you would place the screen. (2 pts) d. Is it possible to view the image formed by the lens with your eye? If so, indicate on the diagram where you would place your eye, and in what direction you would look. (2 pts) Name__________________________________ 22. It’s been determined that the critical angle associated with a particular liquid‐air interface is 45°. a. Determine the index of refraction of the liquid. (3 pts) b. For the light ray shown, carefully indicate the path(s) of the refracted and/or reflected rays – whichever occur. (2 pts) air liquid 23. Which has more resistance – a 1500 W blow dryer or a 500 W toaster? Explain your reasoning. (3 pts) (24‐27) An uncharged parallel plate capacitor is connected to a 6.0 V battery, a bulb, and a switch (initially open) as shown. The switch is then closed. 24. On the axes at right, sketch the voltage vs. time graph that you would predict. (2 pts) (25‐27) The experiment is repeated with a capacitor of greater capacitance. 25. (1 pt) The voltage across the capacitor after a long time will...
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This note was uploaded on 09/15/2013 for the course PHYS 112 taught by Professor Cui during the Fall '08 term at UMBC.

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