Chapter 21

# Chapter 21 - Chapter 21: ELECTRIC CHARGE 1. A coulomb is...

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Chapter 21: ELECTRIC CHARGE 1. A coulomb is the same as: A. an ampere/second B. half an ampere · second 2 C. an ampere/meter 2 D. an ampere · second E. a newton · meter 2 ans: D 2. A kiloampere · hour is a unit of: A. current B. charge per time C. power D. charge E. energy ans: D 3. The magnitude of the charge on an electron is approximately: A. 10 23 C B. 10 23 C C. 10 19 C D. 10 19 C E. 10 9 C ans: D 4. The total negative charge on the electrons in 1 mol of helium (atomic number 2, molar mass 4) is: A. 4 . 8 × 10 4 C B. 9 . 6 × 10 4 C C. 1 . 9 × 10 5 C D. 3 . 8 × 10 5 C E. 7 . 7 × 10 5 C ans: C 5. The total negative charge on the electrons in 1 kg of helium (atomic number 2, molar mass 4) is: A. 48 C B. 2 . 4 × 10 7 C C. 4 . 8 × 10 7 C D. 9 . 6 × 10 8 C E. 1 . 9 × 10 8 C ans: C Chapter 21: ELECTRIC CHARGE 321

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6. A wire carries a steady current of 2 A. The charge that passes a cross section in 2 s is: A. 3 . 2 × 10 19 C B. 6 . 4 × 10 19 C C. 1 C D. 2 C E. 4 C ans: E 7. A wire contains a steady current of 2 A. The number of electrons that pass a cross section in 2 s is: A. 2 B. 4 C. 6 . 3 × 10 18 D. 1 . 3 × 10 19 E. 2 . 5 × 10 19 ans: E 8. The charge on a glass rod that has been rubbed with silk is called positive: A. by arbitrary convention B. so that the proton charge will be positive C. to conform to the conventions adopted for G and m in Newton’s law of gravitation D. because like charges repel E. because glass is an insulator ans: A 9. To make an uncharged object have a negative charge we must: A. add some atoms B. remove some atoms C. add some electrons D. remove some electrons E. write down a negative sign ans: C 10. To make an uncharged object have a positive charge: A. remove some neutrons B. add some neutrons C. add some electrons D. remove some electrons E. heat it to cause a change of phase ans: D 322 Chapter 21: ELECTRIC CHARGE
11. When a hard rubber rod is given a negative charge by rubbing it with wool: A. positive charges are transferred from rod to wool B. negative charges are transferred from rod to wool C. positive charges are transferred from wool to rod D. negative charges are transferred from wool to rod E. negative charges are created and stored on the rod ans: D 12. An electrical insulator is a material: A. containing no electrons B. through which electrons do not f ow easily C. that has more electrons than protons on its surface D. cannot be a pure chemical element E. must be a crystal ans: B 13. A conductor is distinguished from an insulator with the same number of atoms by the number of: A. nearly free atoms B. electrons C. nearly free electrons D. protons E. molecules ans: C 14. The diagram shows two pairs of heavily charged plastic cubes. Cubes 1 and 2 attract each other and cubes 1 and 3 repel each other. 1 2 1 3 Which of the following illustrates the forces of cube 2 on cube 3 and cube 3 on cube 2?

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## This note was uploaded on 11/21/2011 for the course PHYS 2425 taught by Professor . during the Spring '11 term at San Jacinto.

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Chapter 21 - Chapter 21: ELECTRIC CHARGE 1. A coulomb is...

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