Chapter 22 Electrostatics
Exercises
7. Electrons rubbed from plastic onto wool. Plastic bag has a + charge.
10. Discharge charges from cars to protect the toll collector.
11. Purpose is to discharge charges created from friction with air and the road. Electrically-conducting tires are used today.
14. Charged body close to the ball will polarize - attracting unlike and repelling like charges. This charge separation is due to induction.
15. Negative Charge - the penny will have more electrons and will be slightly more massive. Positive Charge - the penny will have less electrons and will be slightly less massive.
19. Inner electrons feel the pull of the nucleus and a large amount of energy is necessary to ionize them.
25. Half the distance the electric field is four times as strong; quarter the distance it is 16 times as strong; four times the distance it is one-sixteenth as strong.
38. The tree and ground near it are raised to a high potential. With legs far apart one leg is on higher potential ground. Lie down and there is a high potential between your head and feet.
51. 10 joules per coulomb is 10 volts. Release and the 10 joules of potential energy becomes 10 joules of kinetic energy.
53. Voltage = 0.5 J / 0.0001 C = 5,000 V
Problems
1. Twice as far is one quarter the force; 5 N
5. (USE radius 0.53X10e-10 - same as lab)
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Fgrav = 3.6X10-47 N and Felec = 8.2X10-8 N . |
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The electrical force between the electron and proton is 2X1039 times greater (2 followed by 39 zeros) than the mass force. |
7. Voltage = potential energy / charge, so potential energy = charge * Voltage = 2 C * 100X10e6 V = 2X10e8 J
10. a. Voltage = potential energy / charge = 12 J / 0.0001 C = 120,000 V
b. 24 J / 0.0002 C = 120,000 V