Unformatted text preview: Electric Current Practice Problems
Current and Resistance
1. Thirtysix Coulombs of electrons enter the left side of wire and exit the right side during a 3 second time interval. W hat is the current in the wire? In what direction is the current? How much cha rge would pass through the wire in 4.23 seconds? 2. A vertical wire contains an upwards current of 29 Amperes. In what direction do the electrons flow? How much charge passes through the wire in 3.2 seconds? How many electrons are involved? 3. A 6 Volt battery i s connected to a radio that draws 0.02 Amperes of current. What is the resistance of the radio? How much charge is used in 3 hours? 4. A light bulb connected to a 120 Volt source of el ectricity has a resistance of 3 2 Ohms. Calculate the current through the bulb. 5. How much voltage will be needed to pass 5 Amperes of current through a toaster with a resistance of 24 Ohms? How much charge will pass through the toaster if it take s 3 minutes to brown the toast? 6. A 1.5 Volt battery supplies 25 milliamps to an electron ic circuit. What is the circuit’s resistance? 7. A 220 Ohm resistor is connected to a 6 Volt source of electricity. How much current flows in milliamps? Ohm’s Law
8. W hich of the electric appliances obeys Ohm’s Law? Explain your reasoning . Applied Voltage 20 Volts 40 Volts 60 Volts 80 Volts Insidetheskin Tomato Twaddler 2 Amps 4 Amps 16 Amps 64 Amps Chuck Norris Bad guy Beaterupper 3 Amps 4 Amps 5 Amps 6 Amps Georg Ohmman SPAM Grill 3 Amps 6 Amps 9 Amps 12 Amps Light Bulb 1 Amp 2 Amps 2.5 Amps 2.75 Amps Electric Energy Use
9. Assume the cost of electricity is 13 cents per kilowatt hour. Calculate the energy used and its cost for the use of the following items: a. 4 W att night light for 8 hours b. 1300 Watt microwave for 10 minutes c. 500 Watt Georg Ohm man electric grill for 35 minut es d. 60 Watt light bulb 6 hours a day for one year e. 300 Watt refrigerator for 3 hours a day for one month 10. Assume the cost of electricity is 17 cents per kilowatt hour. Calculate the power, energy used and its cost for the use of the following items connected to a 120 Volt electric outlet: a. 0.5 Amp computer monitor for 12 hours b. 10 Amp hair dryer for 5 minutes c. 3 Amp electric drill for 30 seconds d. 25 Amp electric clothes dryer connected to 240 Volts for 30 minutes Series Circuits
11. For each of the components listed below, draw a schematic diagram for a series circuit , find the equivalent resistance and current of the circuit, and calculate the voltages, currents and power use of each compone nt: a. Three resistors of 10, 15 and 20 Ohms connected to a 12 Volt battery. b. Three resistors of 6, 12 and 18 Ohms connected to a 120 Volt power supply. c. Two 100 Ohm resistors connected to a 6 Volt battery. d. Three 100 Ohm resistors connected to a 6 Volt battery. e. Five resistors of 100, 10, 10, 1 0, and 20 Ohms connected to a 1.5 Volt battery. Parallel Circuits
12. For each of the components listed above, draw a schematic diagram for a parallel circuit , find the equivalent resistance and current of the circuit, and cal culate the voltages, currents and power use of each component.
R1 Combination Circuits
13. Calculate the equivalent resistance and complete a VIRP table for Circuit A for the sets of components shown. a. Battery of 6 Volts, R 1 = 10 Ohms, R 2 = 15 Ohms, and R 3 = 20 Ohms b. Battery of 6 Volts, R 1 = 20 Ohms, R 2 = 15 Ohms, and R 3 = 10 Ohms c. Battery of 1.5 Volts, R 1 = 30 Ohms, R 2 = 40 Ohms, and R 3 = 50 Ohms d. Battery of 12 Volts, R 1 = 100 Ohms, R 2 = 220 Ohms, and R 3 = 330 Ohms 14. Calculate the equivalent resistance and compl ete a VIRP table for Circuit B for the sets of components shown above.
R2 R2 R3 Circuit A 15. Calculate the equivalent resis tance and complete a VIRP table for the 5 resistor circuit below with a 9 Volt battery and five resistors of R1 = 440 Ohms, R2 =330 Ohms, R3 = 220 Ohms, and R4 = R5 =100 Ohms .
R3 R1 R3 R1 R2 R4 R5 Circuit B Answers: 1. 12 A, right to left, 50.76 Coulombs 2. Downwards, 92.8 Coulombs, 5.8 x 10 20 3. 300 Ω, 216 Coulombs 4. 3.75 A 5. 120 Volts, 900 Coulombs 6. 60 Ω 7. 27.3 mA 8. The grill has the same resistance for all voltages. 9. 0.032 kW h, $0.004 16; 0.2167 kW h, $0.02817; 0.2917 kW h, $0.03792; 131.4 kW h, $17.08; 27 kW h, $3.51 10. 60 W, 0.72 kW h, $0.1224; 1200 W, 0.1 kW h, $0.013; 360 W, 0.003 kW h, $0.0005; 6000 W, 3 kW h, $0.51 11. Series circuits a. 45 Ohms; 0.2667 Amps; 2.667 Volts; 4.000 Volts; 5.334 Volts; 0.7113 Watts; 1.067 Watts; 1.423 Watts b. 36 Ohms; 3.333 Amps; 20 Volts; 40 Volts; 60 Volts; 66.66 Watts; 133.3 Watts; 200 Watts c. 200 Ohms; 30 mA; 3 Volts; 3 Volts; 9 mW; 9 mW d. 300 Ohms; 20 mA; 2 Volts; 2 Volts; 2 Volts; 4 mW; 4 mW; 4 mW e. 150 Ohms; 10 mA; 1 Volt; 0.1 Volts; 0.1 Volts; 0.1 Volts; 0.2 Volts; 10 mW; 1 mW; 1 mW; 1 mW; 2 mW 12. Parallel Circuits a. 4.615 Ohms; 2.6 Amps; 1.2 Amps; 0.8 Amps; 0.6 Amps; 12 Volts each; 14.4 Watts; 9.6 Watts; 7.2 Watts b. 3.273 Ohms; 36.67 Amps; 20 Amps; 10 Amps; 6.67 Amps; 120 Volts each; 2400 Watts; 1200 Watts; 800 W atts c. 50 Ohms; 4.8 Amps; 2.4 Amps; 2.4 Amps; 6 Volts each; 14.4 Watts; 14.4 Watts d. 33.33 Ohms; 9.6 Amps; 2.4 Amps; 2.4 Amps; 2.4 Amps; 6 Volts each; 14.4 Watts; 14.4 Watts; 14.4 Watts e. 2.778 Ohms; 0.54 Amps; 15 mA; 0.15 Amps; 0.15 Amps; 0.15 Amps; 75 mA; 1.5 Vo lts each; 81 mW; 0.225 Watts; 0.225 Watts; 0.225 Watts; 0.1125 Watts 13. Circuit A a. Req = 26 Ohms; Itotal = 0.2308 Amps V (Volts) I (Amps) R (Ohms) P (Watts) 1.385 1.385 4.615 6.000 0.138 0.092 0.231 0.231 10.000 15.000 20.000 26.000 0.192 0.128 1.065 1.385 b. Req = 23.57 Ohms; Itotal = 0.2545 Amps V (Volts) I (Amps) R (Ohms) P (Watts) 2.182 2.182 3.818 6.000 0.109 0.145 0.255 0.255 20.000 15.000 15.000 23.571 0.238 0.317 0.972 1.527 Req = 67.14 Ohms; Itotal = 22.3 milliAmps V (Volts) I (Amps) R (Ohms) P (Watts) 0.383 0.383 1.117 1.500 0.013 0.010 0.022 0.022 30.000 40.000 50.000 67.143 0.0049 0.0037 0.0250 0.0335 c. Req = 398.75 Ohms; Itotal = 30.1 milli Amps V (Volts) I (Amps) R (Ohms) P (Watts) 2.069 2.069 9.931 12.000 0.021 0.009 0.030 0.030 100.000 220.000 330.000 398.750 0.0428 0.0195 0.2989 0.3611 14. Circuit B a. Req = 7.778 Ohms; Itotal = 0.7714 Amps V (Volts) I (Amps) R (Ohms) P (Watts) 6.000 2.571 3.429 6.000 0.600 0.171 0.171 0.771 10.000 15.000 20.000 7.778 3.600 0.441 0.588 4.629 b. Req = 11.11 Ohms; Itotal = 0.5400 Amps V (Volts) I (Amps) R (Ohms) P (Watts) 6.000 3.600 2.400 6.000 0.300 0.240 0.240 0.540 20.000 15.000 10.000 11.111 1.800 0.864 0.576 3.240 c. Req = 22.50 Ohms; Itotal = 66.7 milliAmps V (Volts) I (Amps) R (Ohms) P (Watts) 1.500 0.667 0.833 1.500 0.050 0.017 0.017 0.067 30.000 40.000 50.000 22.500 0.075 0.011 0.014 0.100 d. Req = 84.615 Ohms; Itotal = 0.1418 Amps V (Volts) I (Amps) R (Ohms) P (Watts) 12.000 4.800 7.200 12.000 0.120 0.022 0.022 0.142 100.000 220.000 330.000 84.615 1.440 0.105 0.157 1.702 15. Five resistor circuit Req = 458.6 Ohms; Itotal = 19.63 milliAmps V (Volts) I (milliAmps) R (Ohms) P (milliWatts)
3.701 3.701 4.318 0.9815 0.9815 9 8.411 11.22 19.63 9.815 9.815 19.63 440 330 220 100 100 458.6 31.13 41.45 84.76 3.701 3.701 176.67 ...
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 Fall '08
 Bocker
 Physics, Current, Resistance, Volt, Ohms, Resistor, Electrical resistance, Ampere

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