Select the response that best answers the given statement. Be sure to write all final multiple choice answers on your Scantron answer sheet.

Transcription

1 Chapters PHYS Brooks This practice test is similar to the actual final. The final exam will focus on questions involving solving problems, and not so much on conceptual questions. The final will consist of about 25 questions designed to be completed in about 2 hours. This practice test does not cover every single concept that may be on the final. A few of the questions here are from previous class exams, but most are new. The final exam will consist of all new questions but will cover concepts covered throughout the semester. This practice exam includes an answer key, but there are no solutions to the problems. Students need to work out all solutions on their own. Select the response that best answers the given statement. Be sure to write all final multiple choice answers on your Scantron answer sheet. 1. Two point charges each have a value of 3.0 C and are separated by a distance of 4.0 m. What is the electric field at a point midway between the two charges? a. zero b. 9.0X107 N/C c. 18X107 N/C d. 4.5X107 N/C 2. As the velocity of your spaceship increases, you would observe a. that your precision clock runs slower than normal. b. that the length of your spaceship has decreased. c. that your mass has increased. d. all of the above. e. none of the above. 3. A parallel plate capacitor is constructed with plate area of 0.40 m2 and a plate separation of 0.10 mm. How much charge is stored on it when it is charged to a potential difference of 12 V? a μc b μc c μc d μc 4. You are designing a generator with a maximum emf 8.0 V. If the generator coil has 200 turns and a cross-sectional area of m2, what would be the frequency of the generator in a magnetic field of T? a. 7.1 Hz b. 7.5 Hz c. 8.0 Hz d. 44 Hz

2 5. A plane mirror forms an image that is a. real and upright. b. virtual and upright. c. real and upside down. d. virtual and upside down. 6. An object is 15 mm in front of a converging lens, and the image is 4.0 mm behind the lens. What is the focal length of the lens? a. 11 mm b. 5.5 mm c. 3.8 mm d. 3.2 mm 7. A soap bubble has an index of refraction of What minimum thickness of this bubble will ensure maximum reflectance of normally incident 530 nm wavelength light? a nm b nm c. 199 nm d. 398 nm 8. Doubling the voltage across a given capacitor causes the energy stored in that capacitor to a. quadruple. b. double. c. reduce to one half. d. reduce to one fourth. 9. A piece of plastic has a net charge of μc. How many more protons than electrons does this piece of plastic have? a X 1013 b X 1019 c X 1013 d X A 14 A current flows into a parallel combination of a 3.0 Ω and a 4.0 Ω resistor. What current flows through the 3.0 Ω resistor? a. 8.0 A b. 7.0 A c. 6.0 A d. 5.0 A 11. During a reaction, 1.7 X 10-4 J of energy is released. What change of mass would cause this? a. 5.1 X 10-4 kg b. 1.5 X kg c. 4.8 X kg d. 1.9 X kg

3 12. Three point charges are located at the following positions: Q1 = 2.00 μc at x = 1.00 m; Q2 = 3.00 μc at x = 0; Q3 = μc at x = m. What is the magnitude of the force on the 3.00 μc charge? a X 10-2 N b N c X 10-2 N d N 13. What resistance is needed in a series circuit with a 20 mh coil and 1.0 μf capacitor for a total impedance of 100 Ω at 1500 Hz? a kω b. 82 Ω c. 57 Ω d. 18 Ω 14. The current through a 50- Ω resistor is I = 0.80 sin (240 t). How much power is dissipated in the resistor? a. 16 W b. 32 W c. 45 W d. 64 W 15. A convex lens has focal length f. An object is located at infinity. The image formed is located a. at 2f. b. between f and 2f. c. at f. d. between the lens and f. 16. If a Cu2+ ion drops through a potential difference of 12 V, it will acquire a kinetic energy (in the absence of friction) of a. 3.0 ev b. 6.0 ev c. 12 ev d. 24 ev 17. A 10 Ω resistor is in series with a 100 μf capacitor at 120 Hz. What is the phase angle? a. 82 o b. 53 o c. 37 o d. 4.7 o 18. Nearsightedness can usually be corrected with a. converging lenses. b. diverging lenses. c. achromatic lenses. d. cylindrical lenses.

4 19. A laser beam strikes a plane's reflecting surface with an angle of incidence of 37 o. What is the angle between the incident ray and the reflected ray? a. 37 o b. 74 o c. 45 o d. 90 o 20. Q1 = 6.0 nc is at (0.30 m, 0); Q2 = -1.0 nc is at (0, 0.10 m); Q3 = 5.0 nc is at (0, 0). What is the direction of the net force on the 5.0 nc charge? a. 34 o above +x axis b. 34 o below -x axis c. 56 o above +x axis d. 56 o below -x axis 21. The uncertainty in the position of a proton is nm. What is the uncertainty in its speed? a m/s b. 975 m/s c. 600 m/s d. 2.2 m/s 22. Capacitances of 10 μf and 20 μf are connected in parallel, and this pair is then connected in series with a 30 μf capacitor. What is the equivalent capacitance of this arrangement? a. 10 μf b. 15 μf c. 25 μf d. 60 μf 23. When light of wavelength 350 nm is incident on a metal surface, the stopping potential of the photoelectrons is ev. What is the threshold frequency? a X 1014 Hz b X 1014 Hz c X 1014 Hz d X 1014 Hz 24. A microscope has an objective lens of focal length 1.40 mm and an eyepiece of focal length 20.0 mm, adjusted for minimum eyestrain. A blood sample is placed 1.50 mm from the objective. What is the overall magnification? a b c. 175 d. 367

5 25. The kinetic energy of a proton is 80% of its total energy. What is the speed of the proton? a. 0.02c b. 0.87c c. 0.98c d. 1.0c 26. A spaceship moves away from the Earth with a speed of 0.80c. The spaceship then fires a missle with a speed of 0.50c relative to the spaceship. What is the velocity of the missle measured by observers on the Earth if the missle is fired toward the Earth? a. 0.30c b. 0.50c c. 0.93c d. 1.3c 27. How much mass is lost during a reaction in which 1.7 X 108 MeV of energy is released? a. 1.8 X 10-8 kg b. 5.7 X 10-9 kg c. 1.9 X kg d. 3.0 X kg 28. An electron moves with a speed of 8.0 X 106 m/s along the +x axis. It enters a region where there is a magnetic field of 2.5 T, directed at an angle of 60ø to the +x axis and lying in the xy plane. Calculate the acceleration of the electron. a. 1.3 X 1018 m/s2 b. 3.1 X 1018 m/s2 c. 1.3 X m/s2 d. 3.1 X m/s2 29. A circular loop of wire of radius 0.50 m is in a uniform magnetic field of 0.30 T. The current in the loop is 2.0 A. What is the magnetic torque when the plane of the loop is at 30 o to the magnetic field? a. zero b m-n c m-n d m-n 30. A parallel-plate capacitor consists of plates of area 1.5 X 10-4 m2 and separated by 1.0 mm. The capacitor is connected to a 12-V battery. What is the electric field between the plates? a. 12 V/m b. 1.2 X 102 V/m c. 1.2 X 103 V/m d. 1.2 X 104 V/m

6 31. What is the total energy of an electron moving with a speed of 0.95c? a. 2.6 X J b. 8.2 X J c. 1.1 X J d. 1.2 X J 32. A 5.0-nC charge is at (0, 0) and a -2.0 nc charge is at (3.0 m, 0). If the potential is taken to be zero at infinity, what is the electric potential energy of a 1.0-nC charge at point (0, 4.0 m)? a. 1.5 X 10-8 J b. 3.6 X 10-9 J c. 1.1 X 10-8 J d. 1.9 X 10-8 J 33. A concave spherical mirror has a focal length of 20 cm. An object is placed 30 cm in front of the mirror on the mirror's axis. Where is the image located? a. 12 cm in front of the mirror. b. 60 cm behind the mirror. c. 60 cm in front of the mirror. d. None of the above. 34. Light has a wavelength of 600 nm in a vacuum. It passes into glass, which has an index of refraction of What is the speed of the light in the glass? a. 3.0 X 108 m/s b. 2.5 X 108 m/s c. 2.0 X 108 Hm/s d. 1.5 X 108 m/s 35. A proton is accelerated from rest through 500 V. It enters a magnetic field of 0.30 T oriented perpendicular to its direction of motion. Determine the radius of the path it follows. a. 1.1 mm b. 1.1 cm c. 11 cm d. 1.1 m 36. A charge of 60 μc is placed on a 15 μf capacitor. How much energy is stored in the capacitor? a. 120 J b. 4.0 J c. 240 μj d. 120 μj 37. How many joules of energy are required to accelerate one kilogram of mass from rest to a velocity of c? a. 1.8 X 1017 J b. 9.0 X 1016 J c. 3.0 X 103 J d. None of the above

7 38. The flux through a coil changes from 4.0 X 10-5 Wb to 5.0 X 10-5 Wb in 0.10 s. What emf is induced in this coil? a. 5.0 X 10-4 V b. 4.0 X 10-4 V c. 1.0 X 10-4 V d. None of the above A of current flows through 8.0 Ω for 24 hours. How much does this cost if energy costs $0.09/kWh? a. $0.24 b. $1.04 c. $2.16 d. $ If EMF = 20 V, what is the current through R3? a A b A c. 1.0 A d. 4.0 A 41. How much energy, in joules, is carried by a photon of wavelength 660 nm? a x J b x J c x J d. None of the above A is flowing through an 8.00 Ω resistor. How much power is being dissipated? a W b. 128 W c. 256 W d kw 43. Suppose that the speed of an electron traveling 2000 m/s is known to an accuracy of 1 part in 105 (i.e., within 0.001%). What is the greatest possible accuracy within which we can determine the position of this electron? a. 2.9 mm b. 5.8 mm c. 8.7 mm d. 1.2 cm

8 44. In a transformer, how many turns are necessary in a 110 V primary if the 24 V secondary has 100 turns? a. 458 b. 240 c. 110 d What is the Q value for the following reaction? 7Li + 1p = 4He + 4He ( ) ( ) ( ) ( ) a MeV b MeV c MeV d MeV

9 ANSWER KEY 1. a 2. e 3. b 4. a 5. b 6. d 7. b 8. a 9. a 10. a 11. d 12. d 13. c 14. a 15. c 16. d 17. b 18. b 19. b 20. d 21. a 22. b 23. d 24. d 25. c 26. b 27. d 28. b 29. b 30. d 31. a 32. c 33. c 34. c 35. b 36. d 37. b 38. c 39. d 40. b 41. b 42. b 43. b 44. a 45. c