Chapter #11 Solutions - Physical Science with Modern Applications - Melvin Merken - 5th Edition

 

1. If a positively charged glass rod attracts a pith ball suspended by a silk thread, must the pith ball be negatively charged? Explain. Get solution

2. Although rubbing a ball-point pen with a piece of flannel is not essential for electrifying the pen, it acquires a stronger charge than when it is merely in contact with the flannel. Explain. Get solution

3. Why is repulsion rather than attraction a conclusive test of electrification? Get solution

4. An unknown charge is brought near the knob of a positively charged electroscope, and the leaves converge. What is the nature of the unknown charge? Get solution

5. Assuming that an object is charged, explain how you would decide whether the charge is positive or negative. Get solution

6. Why is it more difficult to maintain an electric charge on an electroscope on a damp day than on a dry day? Get solution

7. Explain how you would charge an electroscope negatively by induction. Get solution

8. Explain how a charged body attracts an uncharged one. Get solution

9. Why do small bits of dry paper that are attracted to a charged comb often fly away when they touch the comb? Get solution

10. Explain why you may receive a shock from a metal door handle when you slide across a seat in an automobile. Get solution

11. The atoms of conductors and insulators are composed of the same constituents: electrons, protons, and neutrons. In what way, then, do conductors and insulators differ? Get solution

12. Name (a) three good conductors of electricity, and (b) three good insulators. Get solution

13. (a) In what ways are electrical forces and gravitational forces similar? (b) In what ways do they differ? Get solution

14. In hydrogen, the simplest atom, the electron and the proton (nucleus) are separated by 0.530 angstrom unit. If the charge on each is 1.60 × 10−19 coulomb (–for the electron, + for the proton), what is the force between them? Get solution

15. Calculate the force between two electrons that are separated by 10−9 meter. (Charge on the electron is − 1.60 × 10−19 coulomb.) Get solution

16. Explain the discharge of a lightning stroke between a negatively charged cloud and the earth. Get solution

17. How does an automobile that has a metal top and body shield its occupants from lightning? Get solution

18. Why is standing in an open field during a thunderstorm a dangerous practice? Get solution

19. (a) In what ways are electric charges and magnetic poles similar? (b) Different? Get solution

20. Why may heating reduce the strength of a magnet? Get solution

21. Discuss the significance of Faraday’s and Henry’s discovery of the production of an electric current by means of magnetism. Get solution

22. Can you create monopoles by breaking a bar magnet in half? Explain. Get solution

23. Like poles repel, yet the north-seeking pole of a magnet is attracted to the geographic North Pole of the earth. Explain. Get solution

24. Explain why a nail is attracted to either pole of a magnet, but another magnet is attracted to only one of the poles. Get solution

25. A magnet can be weakened by dropping it on a hard floor. Explain. Get solution

26. The atoms in a piece of wood are tiny magnets, yet the piece of wood is not. Explain. Get solution

27. Why will an unmagnetized nail that is in contact with a magnet attract an unmagnetized paper clip? Get solution

28. Discuss the meaning of the term “electric field.” Get solution

29. Calculate the magnitude and direction of the electric field 3.00 meters from a positive charge of 10−5 coulomb. Get solution

30. Sketch the electric field pattern between two point charges of opposite sign separated by a small distance. Get solution

31. (a) Two bar magnets are placed with their south poles facing each other. Represent the magnetic field between them in a diagram.(b) Repeat with the north pole of one magnet opposite the south pole of the second magnet. Get solution

32. A transistor radio draws 0.500 ampere of current. If it uses a 9.00-volt battery, what is the resistance of the radio? Get solution

33. What is the current through a 60.0-watt lamp that operates at 120 volts? Get solution

34. How many electrons flow through the filament of a 120-volt, 60.0-watt light bulb per second? Get solution

35. When people say that they left lights in the house “burning,” is this a correct statement? How might it have originated? Get solution

36. An electric clock uses 5.00 milliamperes of current on 120 volts. Find its resistance. Get solution

37. Why is it dangerous to replace a 15-ampere fuse that blows repeatedly with one having a larger current rating? Get solution

38. How much current flows through a 60.0-watt headlight of an automobile that has a 12-volt electrical system? Get solution

39. Calculate the resistance of a vacuum cleaner that uses a current of 14.0 amperes and operates on 120 volts. Get solution

40. Three incandescent lamps with resistances of 220, 440, and 660 ohms are connected in parallel across a 110-volt fine.(a) What is their combined resistance?(b) What total current is drawn by the three lamps?(c) How much current does each lamp draw? Get solution

41. Explain why operating too many electrical devices at one time may cause a fuse to blow. Get solution

42. Are the currents in resistors that are connected in parallel generally the same? Explain. Get solution

43. (a) What is the total resistance of five 20-ohm resistors connected in series? (b) Parallel? Get solution

44. Three resistors of 5, 10, and 15 ohms each are connected in series in a circuit with a 9.0-volt battery. What is the current through each resistor? Get solution

45. A 100-watt lamp draws 0.800 ampere in operation. What is its resistance? Get solution

46. Which uses more energy: a 250-watt TV set in 1 hour or a 1200-watt toaster in 10 minutes? Get solution

47. A 100-watt lamp was accidentally left burning in a storeroom for one week. How much did it cost at 10 cents per kilowatt-hour? Get solution

48. An electric range draws 20 amperes at 240 volts. What does it cost per hour to operate at 10 cents per kilowatt-hour? Get solution

49. Does a 5000-watt heater use twice the energy of a 2500-watt heater? Explain. Get solution

50. Multiple ChoiceA. The force of attraction between two charged spheres can be calculated from(a) Newton's second law.(b) Coulomb’s law.(c) Joule’s law.(d) Ohm’s law.B. An instrument for determining the magnitude of a charge is the(a) Van de Graaff generator.(b) electrostatic precipitator.(c) electroscope.(d) electrophorus.C. An electric current in a wire is a flow of(a) atoms.(b) protons.(c) ions.(d) electrons.D. Regions where the magnetic fields of atoms are fined up in the same direction are known as(a) superconductors.(b) magnetic domains.(c) currents of spinning electrons.(d) dynamos.E. A magnetic field is produced by(a) static negative charges.(b) an electron current.(c) static positive charges.(d) falling water.F. Which of the following substances differs from the others with respect to electricity?(a) plastic(b) glass(c) copper(d) cottonG. A natural magnet is(a) iron.(b) amber.(c) aluminum.(d) lodestone.H. Ohm’s law is correctly expressed by(a) ...(b) ...(c) R = VI.(d) I = VR.I. A fight bulb glows because(a) there is burning inside.(b) an electric current glows.(c) the filament is hot.(d) a very small current is flowing.J. Which of the following does not produce a magnetic field?(a) a current-carrying wire(b) a stationary electric charge(c) a moving electric charge(d) an electromagnet Get solution


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