Capacitor
WORKING OF A CAPACITOR
What is a Capacitor:
Capacitor is a
- basic electrical component that stores electrical energy in the form of electric charge.
- a component consists of two metal plates separated by a small distance. This separation may or may not be filled with dielectric material.
Assume these metal plates are infinitely large, having high conductivity and it can supply or accept any number of electrons.
Working of a Capacitor:
Charging:
Consider a metal plate having high conductivity is connected to the positive terminal of the battery.
The positive terminal of the battery tends to attract large number of electrons from the metal plate (because of high conductivity of the metal plate and large potential difference between the battery and the metal plate).
As the metal plate loses its electrons, positive charge is getting build-up on the plate. This constitutes an electric field.
This electric field tends to attract negative charge from the surrounding (if any).
Now place another metal plate close to the previous one and connect it to the negative terminal of the battery.
Electric field from plate $1$ tends to pull electrons from plate $2$, and the negative terminal of the battery supplies electrons to the metal plate $2$.
This leads to the build-up of negative charge in metal plate $2$.
This charge build-up leads to increase in capacitor voltage.
After some time, the potential difference between battery and capacitor becomes zero. $$V_{battery}=V_{capacitor}$$This means that the capacitor is fully charged. The capacitor remains charged as long as the battery is connected to it (without changing the polarity).
The process of gaining charge by the metal plates of a capacitor is termed as charging.
Discharging:
When the polarity of the battery is changed, (i.e.,) metal plate $1$ is connected to the negative terminal and metal plate $2$ is connected to the positive terminal of the battery,
Metal plate$1$ begins to lose its positive charge by gaining electrons from the battery and Metal plate $2$ begins to lose electrons or its negative charge.
This process of capacitor plates losing its charge is termed as discharging. Once the capacitor is fully discharged, the capacitor voltage will become zero.$$V_{capacitor}=0$$
The process of losing charge by the metal plates of a capacitor is termed as discharging.
Capacitor can also be discharged by connecting it to a load like electric bulb, motor, etc.,