Flashcards
A2 Physics Capacitance
Cards in this deck (10)
- 1Function of capacitorsStoring energy
- 2DielectricAn electrical insulator
- 3How does a capacitor store energyOn a capacitor, there is a separation of charge with +ve on one plate and -ve on the other
To separate the charges, work must be done hence energy is released when charges come together - 4CapacitanceThe ratio of charge stored by a capacitor to the potential difference across it
Q = CV
The capacitance of a capacitor is directly proportional to the area of the plates and inversely proportional to the distance between the plates - 5FaradUnit of Capacitance
- 6How an electric field can cause air to become conducting (Dielectric breakdown)The electric field causes forces in opposite directions on the electrons and nucleus of atoms in air
This results in the field causing electrons to be stripped off the atom
Results in a spark - air now contains oppositely charged particles which can carry charge - 7How to add capacitors in parallelC = C1 + C2 + C3
Because Q = CV
Voltage remains constant
Total charge is all charge on the capacitors added together - 8How to add capacitors in series1/C = 1/C1 + 1/C2 + 1/C3
Because Q = CV
Q is constant in series
Total voltage is calculated by 1/C added x Q - 9Capacitance of a bodyAny isolated body can have a capacitance
Considering a sphere of radius r carrying charge Q, the potential at the surface is
V = Q / (4 pi perm r ) - 10How to calculate energy stored in a capacitorArea under a potential - charge graph is equal to work done
W = 1/2 Q V or 1/2 C V^2
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- AS level Physics Flashcards on A2 Physics Capacitance, created by Sean Byrne on 21/02/2018.
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- Sean Byrne
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