A2 Advancing Physics - OCR B (Capacitance)

HideShow resource information
Preview of A2 Advancing Physics - OCR B (Capacitance)

First 179 words of the document:

How much charge a capacitor can keep separated at a given Potential Difference.
The amount of charge stored per volt
C = Capacitance, Q = Charge, V = Potential Difference
Capacitance is measured in Farads or µF
The simplest form of capacitor consists of two insulated conducting platesthat face each other.
As the electrons flow from one plate to the other, one becomes negatively charged as it gains the
electrons and the other becomes positively charged due to the loss of electrons. This means that the
plates gain equal and opposite amounts of charge and thus a potential difference.
Initially the current is high.
However, as the charge builds up on the plates, it becomes harder for more electrons to be deposited due
to electrostatic repulsion.
When the potential difference across the battery is equal to the potential difference across the capacitor,
the current falls to 0.
I = t
I = Current, Q = Charge, t = Time

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

E= 12 QV
E = Energy on a capacitor, Q = Charge, V = potential difference
2 CV
E = Energy on a capacitor, C = Capacitance, V = potential difference
When the capacitor is connected around a resistor, the current flows in the opposite directionfrom the
charging current. The capacitor starts to discharge.
The capacitor is fully discharged when the potential difference and the current are both zero.
The amount of charge left on the plates decreases exponentiallywith time.…read more

Page 3

Preview of page 3

Here's a taster:

Q = Q0 eRC
Q = Charge left on plates, Q0= charge of capacitor when fully charged, t = Time, RC = time constant
The graphs for potential differenceor currentagainst timefor charging and discharging are also
exponential.…read more


No comments have yet been made

Similar Physics resources:

See all Physics resources »See all resources »