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Name ______________________________ Class ___________________ Date __________________ Chapter 17 Test A Electricity In the space provided, write the letter of the term or phase that best completes each statement or best answers each question. (3 points each) _____ 1. There is a repulsive force between two charged objects when a. their charges are of unlike sign. b. they have the same number of protons. c. their charges are of like sign. d. they have the same number of electrons. _____ 2. Electric force varies depending on the a. charge and distance between charged objects. b. charge and mass of charged objects. c. height and mass of charged objects. d. mass and distance between charged objects. _____ 3. Batteries typically have a. two positive terminals. b. two negative terminals. c. one positive and one negative terminal. d. no terminals. _____ 4. An electric current is produced when charges are accelerated by an electric field to move to a position of potential energy that is a. higher. c. equal. b. lower. d. infinite. _____ 5. Resistance is caused by a. internal friction. c. proton charge. b. electron charge. d. kinetic energy. _____ 6. The SI unit of resistance is the a. volt. c. ohm. b. ampere. d. joule. _____ 7. What is the potential difference across a resistor that dissipates 5.00 W of power and has a current of 5.0 A? a. 1.0 V c. 125 V b. 4.00 V d. 0.20 V _____ 8. There is a potential difference of 12 V across a resistor with 0.25 A of current in it. The resistance of the resistor is a. 48 Ω. c. 12 Ω. b. 24 Ω. d. 0.021 Ω. Electricity Name ______________________________ Class ___________________ Date __________________ Chapter Test continued _____ 9. A resistor has a resistance of 280Ω. How much current is in the resistor if there is a potential difference of 120 V across the resistor? a. 160 A c. 0.12 A b. 0.43 A d. 2.3 A _____ 10. What happens to the resistance of a superconductor when its temperature drops below the critical temperature? a. Resistance increases. b. Resistance doubles. c. Resistance drops to zero. d. Resistance is reduced by one half. _____ 11. If a lamp is measured to have a resistance of 120 Ω when it operates at a power of 1.00 102 W, what is the potential difference across the lamp? a. 110 V c. 0.913 V b. 120 V d. 220 V _____ 12. A microwave draws 5.0 A when it is connected to a 120-V outlet. If electrical energy costs $0.090/kW • h, what is the cost of running the microwave for exactly 6 hours? a. $2.70 c. $0.72 b. $1.60 d. $0.32 _____ 13. What happens to the overall resistance of a circuit when too many appliances are connected across a 120-V outlet? a. Resistance is increased. c. Resistance is decreased. b. Resistance remains the same. d. Resistance is zero. _____ 14. There is an attractive force between two charged objects when a. their charges are of unlike sign. b. they have the same number of protons. c. their charges are of like sign. d. they have the same number of electrons. _____ 15. When there is an equal amount of positive and negative charges on an object, the object is a. positively charged. c. neutral. b. negatively charged. d. supercharged. _____ 16. The electric force between charged objects is a. attractive only. c. either attractive or repulsive. b. repulsive only. d. neither attractive nor repulsive. _____ 17. Every charged particle produces a(n) a. negative charge. c. magnetic field. b. positive charge. d. electric field. _____ 18. When compared to a –2 charge, there are Electricity Name ______________________________ Class ___________________ Date __________________ a. an equal number of field lines pointing inward toward a +4 charge. b. twice as many field lines pointing inward toward a +4 charge. c. twice as many field lines pointing outward from a +4 charge. d. half as many field lines pointing outward from a +4 charge. _____ 19. Potential difference is measured in a. amperes. c. coulombs. b. volts. d. joules. _____ 20. Current is the rate at which charges move through a(n) a. conductor. c. voltage. b. insulator. d. joule. _____ 21. A flashlight bulb with a potential difference of 4.5 V across its filament has a power output of 8.0 W. How much current is in the bulb filament? a. 3.7 A b. 1.8 A c. 0.23 A d. 0.56 A _____ 22. A 13-Ω resistor has 0.050 A of current in it. What is the potential difference across the resistor? a. 6.5 V c. 0.065 V b. 0.65 V d. 0.0065 V _____ 23. A set of electric trains are powered by a 9-V battery. What is the resistance of the trains if they draw 3.0 A of current? a. 3 Ω c. 27 Ω b. 0.03 Ω d. 2.7 Ω _____ 24. An electric toaster has a power rating of 1,100 W at 110 V. What is the resistance of the heating coil? a. 7.5 Ω c. 10 Ω b. 9.0 Ω d. 11 Ω _____ 25. A color television draws about 2.5 A when it is connected to a 120-V outlet. Assuming electrical energy costs $0.060 per kW • h, what is the cost of running the television for exactly 8 hours? a. $1.44 c. $0.14 b. $0.03 d. $0.30 _____ 26. A device that protects a circuit from current overload is called a a. resistor. c. circuit breaker. b. capacitor. d. closed circuit. Electricity Name ______________________________ Class ___________________ Date __________________ Short Answer. Write your response in the space provided. (2 points each) 27. What is charging by friction? _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ 28. What is resistance in a conductor? _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ 29. What is charging by contact? _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ 30. How does the electric force between two charged objects depend on distance? _______________________________________________________________ _______________________________________________________________ 31. You can pick up static electricity by walking on a wool rug in leather-soled shoes. Explain why you are then negatively charged and what happens when you grab for a metal object such as a doorknob. _______________________________________________________________ _______________________________________________________________ Problems. (2 points each). Show your work. 32. A 180-Ω resistor has 0.10 A of current in it. What is the voltage across the resistor? V = I x R _______________________________________________________________ 33. A resistor has a resistance of 1.8 Ω. How much current is in the resistor if there is a potential difference of 3.0 V across the resistor? I = V / R _______________________________________________________________ Electricity Name ______________________________ Class ___________________ Date __________________ Schematic Diagrams (2 points each) 34. Which bulb(s) will have a current in the schematic diagram above? _______________________________________________________________ 35. Does the schematic diagram below represent a series or parallel circuit? _______________________________________________________________ 36. Is a current flowing in the schematic diagram above? Explain your answer. _______________________________________________________________ 37. Does the schematic diagram above represent a series or parallel circuit? _______________________________________________________________ Electricity