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CAIE
19. Capacitance
19.1 Capacitors and capacitance
- define capacitance, as applied to both isolated spherical conductors and to parallel plate capacitors
- recall and use C = Q/V
- derive, using C = Q/V, formulae for the combined capacitance of capacitors in series and in parallel
- use the capacitance formulae for capacitors in series and in parallel
19.2 Energy stored in a capacitor
- determine the electric potential energy stored in a capacitor from the area under the potential–charge graph
- recall and use W = 1/2QV = 1/2CV2
19.3 Discharging a capacitor
- analyse graphs of the variation with time of potential difference, charge and current for a capacitor discharging through a resistor
- recall and use τ = RC for the time constant for a capacitor discharging through a resistor
- use equations of the form x = x0 e–(t/RC) where x could represent current, charge or potential difference for a capacitor discharging through a resistor