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Name: ____________________________________ 1. An electric dryer consumes 6.0 × 106 joules of energy when operating at 220 volts for 30. minutes (1800 seconds). During operation, the dryer draws a current of approximately A. 10. A B. 15 A C. 20. A D. 25 A 2. While operating at 120 volts, an electric toaster has a resistance of 15 ohms. The power used by the toaster is A. 8.0 W B. 120 W C. 960 W D. 1,800 W 3. A clothes dryer connected to a 240-volt line draws 30. amperes of current for 20. minutes (1,200 seconds). Approximately how much electrical energy is consumed by the dryer?
7. If the power developed in an electric circuit is doubled, the energy used in one second is A. quartered B. doubled C. halved D. quadrupled 8. What is the approximate amount of electrical energy needed to operate a 1600-watt toaster for 60. seconds? A. 27 J B. 1500 J C. 1700 J D. 96000 J 9. A lamp and an ammeter are connected to a source as shown in the diagram.
A. 4.8 × 103 J B. 7.2 × 103 J C. 1.4 × 105 J D. 8.6 × 106 J 4. Which is a unit of electrical power? A. volt/ampere B. ampere/ohm C. ampere2 /ohm D. volt2 /ohm 5. A light bulb operating at 120 volts draws a current of 0.50 ampere for 240 seconds. The power rating of the light bulb is A. 30. W B. 60. W C. 75 W D. 120 W 6. An electric motor draws 150 amperes of current while operating at 240 volts. What is the power rating of this motor? A. 1.6 W B. 3.8 × 102 W C. 3.6 × 104 W D. 5.4 × 106 W
What is the electrical energy expended in the lamp in 3.0 seconds? A. B. C. D.
50. J 150 J 50. W 150 W
10. An electric iron draws a current of 5 amperes and has a resistance of 20 ohms. The amount of energy used by the iron in 40 seconds is A. 100 J B. 500 J C. 4,000 J D. 20,000 J 11. A toaster connected to a 120-volt outlet draws a current of 6.0 amperes. How much electrical energy does the toaster use in 5.0 seconds? A. 1.4 × 102 J B. 7.2 × 102 J C. 3.6 × 103 J D. 2.2 × 104 J
12. An operating 75-watt lamp is connected to a 120-volt outlet. How much electrical energy is used by the lamp in 60. minutes (3600 seconds)? A. 4.5 × 103 J B. 2.7 × 105 J C. 5.4 × 105 J D. 3.2 × 107 J 13. A toaster dissipates 1500 watts of power in 90. seconds. The amount of electric energy used by the toaster is approximately A. 1.4 × 105 J B. 1.7 × 101 J C. 5.2 × 108 J D. 6.0 × 10−2 J
14. If the potential drop across an operating 300.-watt floodlight is 120 volts, what is the current through the floodlight? A. 0.40 A B. 2.5 A C. 7.5 A D. 4.8 A 15. As the resistance of a lamp operating at a constant voltage increases, the power dissipated by the lamp A. decreases B. increases C. remains the same
Answer Key for Electric Energy 1. B 6. C 11. C 2. C 7. B 12. B 3. D 8. D 13. A 4. D 9. B 14. B 5. B 10. D 15. A
