5.2.1 CAPACITORS What is 0.0 / 5 ? PhysicsCapacitorsA2/A-levelOCR Created by: upsidedown1004Created on: 26-06-16 14:53 Define capacitance charge per unit potential; difference 1 of 12 Define a Farad coulomb per init volt 2 of 12 What is a capacitor? two metal plates separate day an insulator/ when connected to a source of emf charges on plates are equal and opposite/ stores charge 3 of 12 Describe capacitors in series 1/c1 + 1/c2 .... / voltage is split between components/ charge stored is the same 4 of 12 Describe capacitors in parallel c1 + c2/ voltage across is the same / charge is split between components 5 of 12 Describe the work done by a capacitor work is done when charging and discharging/ work done against repulsive forces/ V vs C graph area under line is W 6 of 12 Describe the discharge of a capacitor through a resistor charge will decrease exponentially wrt time/ as Q=VC and V=IR both voltage and current will decrease in the same way 7 of 12 What is the time constant of a circuit? time taken for the charge to have decreased to 1/e of the original (fall by 37%) 8 of 12 Describe the constant-ratio property of exponential decays 'constant half life' time taken for Q to half is always the same 9 of 12 What does the time taken for a capacitor to charge/discharge depend on? C - amount of charge that can be transferred per unit V/ Resistance affects the current 10 of 12 How long does it take for a capacitor to completely charge/recharge? 5CR 11 of 12 What are the uses of capacitors? takes only a few seconds to charge then can be discharged rapidly - flash bulbs/ back up batteries for computers etc. 12 of 12
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