Current, Resistance, and Electromagnetic Force

# Current, Resistance, and Electromagnetic Force - Capacitor...

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Capacitor Supplies Current to Bulb Part A Immediately after time , what happens to the charge on the capacitor plates? a. Individual charges flow through the circuit from the positive to the negative side of the capacitor. b. Individual charges flow through the circuit from the negative to the positive side of the capacitor. c. The positive and negative charges attract each other, so they stay in the capacitor. d. Current flows clockwise through the circuit. e. Current flows counterclockwise through the circuit. List the letters corresponding to the correct statements in alphabetical order. Do not use commas. For instance, if you think that only statements a and c are correct, write ac. bdCorrect Part B At any given instant after , what is the relationship between the current flowing through the two ammeters, and , and the current through the bulb, ? Correct This is a fundamental result that reflects conservation of charge. In a circuit where elements are arranged in series, the voltage changes as current flows through the circuit, but the current is constant. Otherwise, charge would accumulate in the circuit. In a circuit where elements are arranged in parallel, the opposite is true; all parallel branches have the same voltage, although the current may be different in different branches. This result is formalized in Kirchoff's junction law -- the algebraic sum of currents entering any junction must be zero. (In this law, a current leaving a junction is considered negative). Part C What is the relationship between current and charge? If you are given the charge on the positive plate of the capacitor as a function of time, , what is ? = Correct

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Part D Light bulbs are often assumed to obey Ohm's law, but this is not strictly true, because their resistance increases as the filament heats up at higher voltages. A typical flashlight bulb at full brilliance draws a current of approximately 0.5 A while attached to a 3 V
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## This note was uploaded on 08/12/2009 for the course PHY 122 taught by Professor L.rose during the Fall '07 term at New Mexico Junior College.

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Current, Resistance, and Electromagnetic Force - Capacitor...

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