A rubber balloon has become negatively charged from being rubbed with a wool cloth, and the charge is measured as 1.00 × 10-14 C. According to this charge, the balloon contains an excess of how many electrons? Click here to see the answer
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One rubber balloon with a negative charge of 3.00 × 10-14 C is suspended by a string and hangs 2.00 cm from a second rubber balloon with a negative charge of 2.00 × 10-12 C. (a) What is the direction of the force between the balloons? (b) What is the magnitude of the force? Click here to see the answer
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A dry cell does 7.50 J of work through chemical energy to transfer 5.00 C between the terminals of the cell. What is the electric potential between the two terminals? Click here to see the answer
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There is a current of 4.00 A through a toaster connected to a 120.0 V circuit. What is the resistance of the toaster? Click here to see the answer
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A lightbulb with a resistance of 10.0 Ω allows a 1.20 A current to flow when connected to a battery. (a) What is the voltage of the battery? (b) What is the power of the lightbulb? Click here to see the answer
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A small radio operates on 3.00 V and has a resistance of 15.0 Ω. At what rate does the radio use electric energy? Click here to see the answer
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A 1,200 W hair dryer is operated on a 120 V circuit for 15 min. If electricity costs $0.10/kWh, what was the cost of using the blow dryer? Click here to see the answer
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An automobile starter rated at 2.00 hp draws how many amps from a 12.0 V battery?
An average-sized home refrigeration unit has a 1/3 hp fan motor for blowing air over the inside cooling coils, a 1/3 hp fan motor for blowing air over the outside condenser coils, and a 3.70 hp compressor motor. (a) All three motors use electric energy at what rate? (b) If electricity costs $0.10/kWh, what is the cost of running the unit per hour? (c) What is the cost for running the unit 12 hours a day for a 30-day month? Click here to see the answer
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A 15 ohm toaster is turned on in a circuit that already has a 0.20 hp motor, three 100 W lightbulbs, and a 600 W electric iron that are on. Will this trip a 15 A circuit breaker? Explain. Click here to see the answer
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A power plant generator produces a 1,200 V, 40 A alternating current that is fed to a step-up transformer before transmission over the high lines. The transformer has a ratio of 200 to 1 wire loops. (a) What is the voltage of the transmitted power? (b) What is the current? Click here to see the answer
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A step-down transformer has an output of 12 V and 0.5 A when connected to a 120 V line. Assuming no losses: (a) What is the ratio of primary to secondary loops? (b) What current does the transformer draw from the line? (c) What is the power output of the transformer? Click here to see the answer
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A step-up transformer on a 120 V line has 50 loops on the primary and 150 loops on the secondary, and draws a 5.0 A current. Assuming no losses: (a) What is the voltage from the secondary? (b) What is the current from the secondary? (c) What is the power output? Click here to see the answer
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