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Transcript

ELECTRIC CURRENT TEST REVIEW A. Series C. Both 1. 2. 3. 4. 5. 6. 7. 8. 9. B. Parallel D. Neither C Potential difference and current are directly related. A A(n) _____ circuit has only one path. B A(n) _____ circuit has multiple paths. B The resistance decreases as more resistors are added. B The potential difference is the same through all resistors. A The potential difference through all the resistors adds up to the total. D Current will flow if the circuit is open at the charge pump (battery). A The current is the same through all resistors. C Potential difference is supplied by the charge pump (generator). A. Series C. Both B. Parallel D. Neither 10. B When one light goes out, the rest stay on in a _____ circuit. 11. A When one light goes out, so do the rest in a ____ circuit. 12. C Current and resistance are inversely related. 13. A The individual resistors add up to the total resistance. 14. D Light bulbs supply current. 15. B The current through all the resistors adds up to the total. 16. B The voltage drop is the same through all branches of the circuit. 17. B The individual resistors are all larger than the total resistance. 18. B The total (equivalent) resistance is smaller than the resistance of any of the resistors. 19. Symbol (Variable) Measurement: Unit Name: Unit symbol I Potential Difference (voltage) Current R Resistance ohms Ω P Power watts W V Volts V Amps A 20. Which has less resistance? A cold, thick, short wire or a hot, thin, long wire? cold, thick, short wire 21. The rate at which energy is used up by a circuit is called ____. Power 22. The rate at which charge flows through a circuit is called __. Current 23. Identify each statement as True or False: a. F flow of charge is faster than the conventional current. b. T A resistors resistance CANNOT be changed by c. d. e. f. g. h. increasing or decreasing the current. F Electron flow is in the SAME direction as conventional current. T The voltage supplied by a battery does NOT change as the current increases or decreases. T Resistance slows down the current in a circuit. F A 60 W light bulb uses up more energy and draws a greater current than a 100 W light bulb. T Voltage describes the potential difference in a circuit. T A household wall outlet contains 120V. 24. Identify each statement as AC (alternating current) or DC (direct current). a) AC Electrons move back and forth. b) DC Flow of charge is always in one c) d) e) f) direction. DC Used in a flashlight DC Used in a car AC Used in a bathroom light DC As electrons move through a resistor, their voltage drops. 25. Which Diagram shows the correct placement of an ammeter and a voltmeter? ANSWER: D 26. Identify the following Symbols: Light bulb Switch Resistor Voltmeter Battery (Charge Pump Ammeter 27. A gasoline generator converts chemical energy to potential energy. 28. A wind turbine converts kinetic energy to potential energy. 29. A battery converts chemical energy to potential energy. 30. What do you need to form a circuit? battery (charge pump), wires or conductors, and light bulb or other resistor. 31. Calculate the total resistance if you have three resistors in a series circuit that are: 4Ω, 5 Ω, and 7 Ω. 4 + 5 + 7 = 16 ohms 32. Calculate the total resistance in a parallel circuit if there are three resistors that are: 4 Ω, 4 Ω, and 6 Ω. 1/4 + 1/4 + 1/6 = 1.5 ohms USE: V = I●R or P = V●I 33. If a 15 V battery is connected to a light bulb with 5 A of current, what is the resistors value? R = V/I = 15/5 R = 3 ohms 34. What is the potential difference supplied by an appliance that has a resistance of 40 ohms and draws 3 Amps of current? V = IR V = 3 x 40 = 120V 35. A 60 ohm resistor is plugged into a wall outlet, how much current flows through the resistor? (hint – you need to know the voltage in a wall outlet) I = V/R = 120/60 I = 2A USE: V = I●R or P = V●I 36. What is the voltage supplied by a resistor using 12 Watts that draws 4 A of current? P = VI V = P/I = 12/4 = 3V 37. A 45 Watt light bulb is connected to a wall outlet. How much current exists in the light bulb? (hint: you should know the voltage in a wall outlet). P = VI I = P/V = 45/120 = 0.4A 38. A current of 4.5 amps flows through a light bulb and is connected to a 6 volt battery. What much power is the bulb using? P = VI 6 x 4.5 = 27 W 39. Complete the Chart R1 R2 R3 V 100 V I R P Total 12 Ω 33 Ω 22 Ω 40. Complete the Chart: R1 100 Ω R2 300 Ω R3 50 Ω R1 R2 R3 V 12 V I R P Total 100 Ω 300 Ω 50 Ω 41. Identify the following statements as GFCI Outlet, Fuse, or Circuit Breaker: a. GFCI Outlet Protects someone from being electrocuted if they fall into a bath tub with a hair dryer. b. Fuse Found in cars c. Circuit Breaker Found in houses to turn off a circuit if too much current flows. d. GFCI Outlet Found anywhere there is water present. 42. The cost of electricity is $0.09 per kW-h. If a 0.8 kW refrigerator runs for 8 hours, how much will it cost? .8kW x 8 hours = 6.4kW-h x .09 0.58 cents 43. If an appliance uses 500 watts of power, how much energy is used up (kW-h) if it is left on for 3hours? (hint – convert watts to kW first). 500/1000 = .5kW x 3 hours = 1.5kW-h 44. If an appliance runs for 5 minutes (300 seconds) and uses 125,000 J of energy, what is the power rating of the appliance? Use the equation: 125000 J P 300 s P = 416.7 W