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level: Capacitors

Questions and Answers List

level questions: Capacitors

Question	Answer
what are capacitors	devices that can store charge and energy in a DC circuit
what is the formula for capacitance	C=Q/V C is capacitance in farads (F) Q is charge in coulombs (C) V is voltage in volts (V)
what will a graph of charge stored on a capacitor against voltage produce	a straight line through the origin
what is the relationship between charge stored on a capacitor and potential difference	charge is directly proportional to potential difference
what is the gradient on a charge stored on a capacitor against potential difference graph	capacitance
what is the area under the graph on a charge-potential difference graph	energy stored in a capacitor
what are the formulas for energy stored in a capacitor?	E=1/2QV E=1/2CV^2 E=1/2Q^2/C
what does a graph of current against time for a charging capacitor look like	...
describe what happens to current as a capacitor charges	when capacitor is uncharged initially, electrons flow freely to capacitor so current is large as electrons build on one plate of the capacitor they exert a repulsive force on electrons coming on to the capacitor, reducing rate of flow of electrons current decreases and eventually drops to zero when the capacitor is fully charged
what does a graph of potential difference against time look like for a charging capacitor	...
under what conditions only does current flow to a capacitor	when there is a potential difference between the supply and the capacitor
what happens to current when the potential difference across the capacitor is the same as the supply	no more current flows
what is the maximum voltage across a capacitor equal to	the voltage across the supply
what does a graph of current against time look like for a discharging capacitor	...
what does a graph of potential difference against time look like for a discharging capacitor look like	...
what is the effect of resistance on time it takes for a capacitor to charge	the higher the resistance, the longer the capacitor will take to become fully charge
what is the effect on capacitance of a capacitor on time it takes to charge	the higher the capacitance of the capacitor the longer it will take to charge higher capacitance can hold more coulombs of cha