| QUIZ 9 |
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1. The source of all magnetism is |
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a. tiny pieces of iron |
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b. the force of gravity |
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c. electric charge at rest |
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d. nota |
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2. True of False. A current in a conducting wire does not produce a magnetic field. |
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a. True |
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b. False |
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3. A conducting long straight wire loop lies horizontally in the plane of the page. A current flows rightward through the wire. What is the direction of the magnetic field directly above the wire? (It would help if you sketched the straight line and drew an arrow pointing RIGHT on the line representing the current. Hint: Use the right hand rule for long straight wires by pointing your right thumb RIGHTWARD in the direction of the current. Your right fingers will point in the direction of the magnetic field directly above the line.) |
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a. in |
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b. out |
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c. nota |
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4. True or False. A magnetic field exerts a force on a charge in motion. |
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a. True |
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b. False |
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5. True or False. The magnetic force on a charge moving in a magnetic field is not perpendicular to the velocity of the particle. |
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a. True |
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b. False |
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6. True or False. The magnetic force on a charge moving in a magnetic field is not perpendicular to the magnetic field. |
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a. True |
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b. False |
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7. True or False. The magnetic force on a straight, current carrying wire in an external magnetic field is perpendicular to the current. |
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a. True |
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b. False |
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8. True or False. The magnetic force on a straight, current carrying wire in an external magnetic field is perpendicular to the magnetic field. |
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a. True |
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b. False |
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9. 2 long straight wires are parallel and their currents flow in the same direction. The two wires |
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a. attract each other |
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b. repel each other |
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10. True or False. The geographic north pole of the Earth coincides with the Earth's magnetic south pole. |
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a. True |
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b. False |
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11. True or False. Magnetic field lines come out of the north pole and enter the south pole of a magnet. |
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a. True |
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b. False |
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12. True or False. A length of wire is bent into a closed loop and a magnet near the loop is at rest. The current in the loop is zero. |
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a. True |
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b. False |
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13. True or False. A length of wire is bent into a closed loop and a magnet nearby is thrust (moved) into the loop. The current in the loop will be zero. |
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a. True |
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b. False |
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14. A circular loop of copper wire is lying flat on a horizontal table. A bar magnet is held with its South pole downward vertically above the center of the coil. The magnet is released from rest and falls toward the coil. As viewed from above, as it falls, the magnet induces |
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a. a counter-clockwise current in the loop |
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b. a clockwise current in the loop |
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15. According to Faraday's Law, a current flows in a loop of wire when there is a change in |
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a. the electric field intensity through the loop. |
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b. the magnetic field intensity through the loop. |
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16. A device that transforms mechanical energy into electrical energy is a |
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a. generator |
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b. motor |
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c. transformer |
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d. nota |
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17. A device that transforms electrical energy into mechanical energy is a |
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a. generator |
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b. motor |
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c. transformer |
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d. nota |
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18. A big Neon signs requires about 24,000 volts (output voltage) to operate. The "step up" transformer circuit uses a 120-Volt (input voltage) source. What is the ratio of primary to secondary turns on the transformer? |
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a. 1/200 b. 100/1 c. 200/1 d. nota |
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19. True or False. Most of the waves in the
electromagnetic spectrum are invisible to the naked eye. |
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a. True |
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b. False |
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20. The main difference between ganma-ray waves and radio-waves in a vacuum is
the |
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a. wave speed |
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b. wavelength |
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21. Which of these waves has the
largest frequency? |
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a. gamma ray
waves |
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b. infrared waves |
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c. X-Rays |
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d. ultraviolet waves |
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e. light waves |
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22. Which of these waves has the shortest wavelength? |
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a. light waves |
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b. radio waves |
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c. x-rays |
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d. micro-waves |
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23. Which does require a physical medium in which
to travel? |
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a. x-ray waves
b. sound waves |
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24. The natural
frequency of vibrating electrons in atoms of glass is in the |
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a. infrared part of the spectrum |
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b. visible part of the spectrum |
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c. ultraviolet part of the spectrum |
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25. The speed of light in glass is |
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a. more than its speed in a vacuum |
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b. less than its speed in a vacuum |
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c. the same as its speed in a vacuum |
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26. Compared
to its speed in a vacuum, the average speed of a beam of light in water
is |
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a. more |
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b. less |
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c. the same |
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d. nota |
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27. The technical field of “fiber optics” is based mostly
on what principle? |
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(a) light polarization
(b) total internal reflection (c) sound propagation in glass (d) the
alignment of Mars with Venus (s) NOTA |
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28. When a light ray passes from air into glass, the
light ray |
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(a) bends toward the normal line (b) bends away from
the normal line (c) does not change direction (d) nota |
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29. When a light ray passes from water into air, the
light ray |
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(a) bends toward the normal line (b) bends away from
the normal line (c) does not change direction (d) nota |
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30. The virtual image formed by a convex mirror is |
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(a) smaller and closer to the mirror than the object
(b) larger and farther away from
mirror than the object (c) nota |
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31. The virtual image formed by an object close to a concave mirror is |
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(a) smaller and closer to the mirror than the object
(b) larger and farther away from
mirror than the object (c) nota |
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32. The real
image formed by a concave mirror is |
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(a) inverted (upside down) compared to an upright
object (b) upright in the same direction compared to an upright object (c) nota |
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33. A spectacular illustration of dispersion is |
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(a) a mirage (b)
a rainbow (c) nota
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34. Dispersion involves the idea that light waves of
different frequencies in a medium |
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(a) have different amplitudes (b) have different speeds (c) nota |