Capacitor Charging and discharging
Today we will learn how to charge and discharge a capacitor by making a small working model. Capacitors has ability to get charged very quickly and ability to give power very quickly. It is almost used in every electronic circuits. It stores the charge inside and gives it back when needed. A battery eleminator is a good example of using Capacitor. It filters pulsating DC (ripples) and converts it into smooth DC. Capacitors is also widely use to pass AC current.
Unlike battery, capacitor backup is for very short duration but there are many advantage i.e maintanance free, long life, good power efficiency, low current leakage etc. Today supercapacitor is also available which is 20 times more powerfull than normal capacitor if compared with size.
In our experiment we will use Electrolytic capacitor of 1000 Mfd. Electrolytic capacitor have fixed positive and negative terminal marked on it. You can buy its voltage rating of any eg. 1000μF/16V, 1000μF/25V, 1000μF/50V.
fig. A project on Capacitor charging and discharging.
1. Capacitor 1000μF/16V
2. LED 2 Pcs
3. Micro Switch 2 Pcs (other switch will also work.)
4. Resistance 470 or 1K Ohms 2Pcs
A capacitor consists of two conductors separated by a small distance. When the conductors are connected to a charging device (for example, a battery), charge is transferred from one conductor to the other until the difference in potential between the conductors due to their equal but opposite charge becomes equal to the potential difference between the terminals of the charging device.
In our project for charging the capacitor, it connected to battery through switch S1, Resistance R1 and LED 1. Here resistance is used to slow down charging by limiting current (flow of electron) so that we can see few second of charging current using LED connected in series, you can also use Ammeter instead of LED's. When potential of capacitor and battery are equal means fully charged and no current will flow in the circuit in that condition LED will be OFF.
After charging switch off the battery supply. For testing if capacitor charged or not, you can short circuit with a piece of wire, you will see a spark. In our circuit I have placed a LED with a resistance to see few second LED glow and capacitor discharges after few seconds(for that press S2). Resistance here limits current and protects LED.
There are many types of capacitors according to the maximum voltage ability and its charge storage capacity.
a) The ability of a capacitor to store maximum charge (Q) on its metal plates is called its capacitance value (C)
b) One coulomb of charge on a capacitor can be defined as one farad of capacitance between two conductors which operate with a voltage of one volt.
c) The charge of a capacitor is directly proportional to the area of the plates, permittivity of the dielectric material between the plates and it is inversely proportional to the separation distance between the plates.
*You can also use this circuit to test a electrolytic capacitor. Time period will depend on capacitor capacity.
What is Capacitor and how does it work ? View in this video.