A Capacitor is an electrical circuit component. It temporarily stores charge.
It is made of two metal plates separated by an insulator. When a p.d. is put through the capacitor electrons gather on the negative plate whilst the same amount of electrons are removed from the opposite plate
Capacitors only let charge travel in one direction through them.
Capacitance - The ability of a body to store charge (in Farads).
Farad - One unit charge per one unit potential difference
Q = C
V
It is made of two metal plates separated by an insulator. When a p.d. is put through the capacitor electrons gather on the negative plate whilst the same amount of electrons are removed from the opposite plate
Capacitors only let charge travel in one direction through them.
Capacitance - The ability of a body to store charge (in Farads).
Farad - One unit charge per one unit potential difference
Q = C
V
Capacitors in a Circuit
In a parallel circuit, because there is the same p.d. and same charge through each capacitor, the total capacitance is the sum of the capacitors
In a series circuit, because the p.d. is different and there is the same charge through each capacitor, the total capacitance is the sum of the inverse values of the capacitors.
These are the opposite equations to the Resistor equations from AS
Energy of a Capacitor
The area of a Charge to p.d. graph will give he energy of charged capacitor
Discharging of a capacitor
A Capacitor discharges exponentially. This means the ratio remains constant between the starting and final current over an time period
The equations for this discharge are shown below.
Q0 is original charge
I0 is original current
V0 is original voltage
t is time of charging
CR is the time constant (C is capacitance and R is resistance)
I0 is original current
V0 is original voltage
t is time of charging
CR is the time constant (C is capacitance and R is resistance)
Time constant
The time constant is the product of the resistor and capacitor in a circuit.
It is measured in seconds
It is measured in seconds
Working with 'e'
e is a constant like pi.
It is roughly 2.718281828.
On your calculator you will see a 'ln' and 'e^x' button. These stand for natural log and exponential function.
It is roughly 2.718281828.
On your calculator you will see a 'ln' and 'e^x' button. These stand for natural log and exponential function.
Uses
Capacitors are used to remove the bump in the current when an a.c. current is put through a d.c. device - which only likes current in one direction