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Physics 112 Exam 4 Spring 2006 Name_________________ Physics 112 Spring 2006 Exam 4 Thursday, May 4 Directions: This 2-houers exam consists of twenty six multiple-choice questions. The questions on this test are not in order of difficulty. You must mark all of your answers on both your test and the answer sheet. In marking the multiple choice bubble sheet use a number 2 pencil. Do not use ink. If you did not bring a pencil, ask for one. Fill in the appropriate circles completely. If you need to change any entry, you must completely erase your previous entry. Carefully read each question and its five possible answers. Select one and only one answer for each question. Choose the answer that is closest to the correct one. Be sure to write you name on every sheet. You have a sheet in the back of the test that you may use for any extra rough work. When you are finished with the exam, place all exam materials, including the bubble sheet, the exam itself, and scratch paper that you used for the exam, in your folder and return the folder. Good luck! Page 1 of 10 Physics 112 Exam 4 Spring 2006 61. A 5.0 μC charge is placed at the 0 cm mark of a meter stick and a -4.0 μC charge is placed at the 50 cm mark. What is the electric field at the 30 cm mark? A. B. C. D. E. 4.0 × 105 N/C 5.0 × 105 N/C 9.0 × 105 N/C 1.4 × 106 N/C 7.6 × 106 N/C 62. Two 3.00-μC charges are at the ends of a meter stick. Find the electrical potential for the center of the meter stick. A. B. C. D. E. 0 120 V 2.70 × 104 V 5.40 × 104 V 1.08 × 105 V 63. Five identical capacitors, 50 μF each, are connected in parallel, and are then connected to a battery of 3 V. What charge is stored in each capacitor? A. B. C. D. E. 30 μC 60 μC 83 μC 150 μC 750 μC 64. A coffee maker, which draws 13.5 A of current, has been left on for 10 min. What is the net number of electrons that have passed through the coffee maker? A. B. C. D. E. 1.5 × 1022 5.1 × 1022 1.6 × 1019 1.8 × 103 8.1 × 103 Page 2 of 10 Physics 112 Exam 4 Spring 2006 65. A 500-W device is connected to a 120-V ac power source. What is the peak voltage across this device? A. B. C. D. E. 4.2 V 5.9 V 120 V 170 V 220 V 66. What is the total resistance of the circuit below? A. B. C. D. E. 80 Ω 55 Ω 50 Ω 35 Ω 25 Ω 67. An electric field of 1.60 kV/m and magnetic field of 0.400 T act on a moving electron to produce no net force. Calculate the minimum speed of the electron. A. B. C. D. E. 2.00*103 m/s 4.00*103 m/s 6.00*103 m/s 8.00*103 m/s 2.00*102 m/s 68. A current carrying circular loop of wire lies flat on a table top. When viewed from above, the current moves around the loop in a counterclockwise sense. What is the direction of the magnetic field caused by this current, inside the loop? The magnetic field A. circles the loop in a clockwise direction B. circles the loop in a counterclockwise direction C. points straight up D. points straight down E. points North Page 3 of 10 Physics 112 Exam 4 Spring 2006 69. A long solenoid has 200 turns/cm and carries current 1.00A. A sphere of the radius 0.50 cm is placed inside the solenoid. Find the magnetic flux through the sphere. A. B. C. D. E. 0 1.6*10-7 T*m2 4.0*10-8 T*m2 8.0*10-8 T*m2 1.6*10-8 T*m2 70. What is the direction of the induced current in the circular loop due to the decreasing current shown below? I decreasing A. B. C. D. E. counterclockwise clockwise the direction of the current is periodically changing induced current is equal to zero there is not enough information to answer the quastion 71. The coil of a generator has 50 loops and a cross-sectional area of 0.25 m2. What is the maximum emf generated by this generator if it is spinning with an angular velocity of 4.0 rad/s in a 2.0 T magnetic field? A. B. C. D. E. 50 V 100 V 200 V 400 V 600 V 72. An object is located 2.6 m in front of a plane mirror. The image formed by the mirror appears to be A. B. C. D. E. 1.3 m in front of the mirror On the mirror's surface 1.3 m behind the mirror's surface 2.6 m behind the mirror's surface 2.6 m in front of the mirror Page 4 of 10 Physics 112 Exam 4 Spring 2006 73. A concave mirror with a radius of 20 cm creates a real image 30 cm from the mirror. What is the object distance? A. B. C. D. E. 20 cm 15 cm 7.5 cm 5.0 cm 3.0 cm 74. At the first maxima on either side of the central bright spot in a double-slit experiment, light from each opening arrives A. B. C. D. E. in phase 45° out of phase 90° out of phase 180° out of phase none of the given answers 75. Monochromatic light from a distant source is incident on a slit 0.75 mm wide. On a screen 2.00 m away, the distance from the central maximum of the diffraction pattern to the first minimum is measured to be 1.35 mm. Calculate the wavelength of the light. A. B. C. D. E. 506 nm 555 nm 610 nm 709 nm 1012 nm 76. What is the minimum thickness of a nonreflecting film coating (n = 1.30) on a glass lens (n = 1.50) for wavelength 500 nm? A. B. C. D. E. 250 nm 192 nm 167 nm 125 nm 96.2 nm Page 5 of 10 Physics 112 Exam 4 Spring 2006 77. What is the energy difference between the second excited state and first excited state of an electron in the “box” of size L=1nm? A. B. C. D. E. 1.9 eV 1.1 eV 0.6 eV 0.3 eV 0.2 eV 78. If l = 4, which one of the following is a possible quantum number for n? A. B. C. D. E. 0 1 2 4 8 79. A neutral atom has an electron configuration of 1s22s22p63s23p2. What is its atomic number? A. B. C. D. E. 5 11 14 20 28 80. You have 16 kg of a radioactive sample with a certain half-life of 30 years. How much is left after 90 years? A. B. C. D. E. 8 kg 4 kg 2 kg 1 kg nothing 81. When a target nucleus is bombarded by an appropriate beam of particles, it is possible to produce A. B. C. D. E. A less massive nucleus, but not a more massive one. A more massive nucleus, but not a less massive one. A nucleus with smaller atomic number, but not one with a greater atomic number. A nucleus with greater atomic number, but not one with a smaller atomic number. A nucleus with either greater or smaller atomic number. Page 6 of 10 Physics 112 Exam 4 Spring 2006 82. What is the Q-value for radioactive decay reactions? A. B. C. D. E. Q<0 Q>0 Q=0 Sign of Q depends on the nucleus Sign of Q depends on the external conditions 83. What is the nucleus that results in the reaction given below? 2 n 16 8 O ?1 H A. 17 8 O B. 15 8 O C. 15 8 N D. 17 7 N E. 15 7 N 84. How does the total mass of the fission fragments compare to the mass of the original nucleus in a fission reaction? A. B. C. D. E. Fission fragments have more mass Fission fragments have less mass Fission fragments have the same mass It depends on the nucleus It depends on the external conditions 85. A cyclotron operates at 10 MHz. What magnetic field is needed to accelerate protons? A. B. C. D. E. 0.12 T 0.25 T 0.66 T 1.50 T 2.35 T 86. What is the wavelength for a beam of 1.4 GeV electrons? A. B. C. D. E. 8.9 × 10-14 m 8.9 × 10-15 m 8.9 × 10-16 m 8.9 × 10-17 m 8.9 × 10-18 m Page 7 of 10 Physics 112 Exam 4 Spring 2006 Scratch Paper (intentionally left blank). Page 8 of 10 Physics 112 Exam 4 Spring 2006 Record Sheet You may fill in this sheet with your choices, detach it and take it with you after the exam for comparison with the posted answers 61 71 81 62 72 82 63 73 83 64 74 84 65 75 85 66 76 86 67 77 68 78 69 79 70 80 Page 9 of 10 Physics 112 Exam 4 Spring 2006 Answer key 61 71 D. 1.4 × 106 N/C 62 B. 100 V 72 E. 1.08 × 105 V 63 D. 2.6 m behind the mirror's surface 73 D. 150 μC B. 15 cm 64 74 B. 5.1 × 1022 65 81 E. A nucleus with either greater or smaller atomic number 82 B. Q>0 83 E. 75 B. Fission fragments have less mass 85 A. 506 nm 66 76 C. 50 Ω B. 4.00*10 m/s 77 A. 1.9 eV C. points straight up 78 E. 8 3 68 69 C. 0.66 T 86 E. 96.2 nm 67 N 84 A. in phase D. 170 V 15 7 C. 8.9 × 10-16 m 79 A. 0 70 A. counterclockwise C. 14 80 C. 2 kg Page 10 of 10