Edited by Sim, Jen Moreau
- 1 Capacitor:
- 1.1 Construction:
- 1.2 Charging of a Capacitor:
- 1.3 Capacitance of Capacitor & its Unit:
- 1.4 Farad:
- 1.5 Combination of Capacitors:
- 1.6 1. Series combination of Capacitors:
- 1.7 Characteristics Features of Series Combination:
- 1.8 2. Parallel Combination of Capacitors
- 1.9 Characteristic features of Parallel capacitors:
- 1.10 Different Types of Capacitors:
- 2 Referencing this Article
- 3 Comments
The device used to store electric charge and hence electrical energy is called a capacitor.
The simplest capacitor consists of two parallel metal plates placed face to face and separated by air or another insulating material. This medium between the 2 plates is called dielectric.
Charging of a Capacitor:
A capacitor is commonly charged by connecting its plates to the opposite terminals of a battery. In this way, some electrons are transferred through the battery from the positive plate to the negative plate. Charge "+Q" and "-Q" appear on the plates. The mutual attraction between the charges keeps them bound on the inner surface of the two plates and thus the charge remains stored in the capacitor even if the battery is removed. The larger the voltage of the battery, the greater the charge on the capacitor will be.
Q ∝ V
Where 'C' is a constant depending on the geometry of the capacitor. It is known as the capacitance of the capacitor.
Capacitance of Capacitor & its Unit:
The charge stored per unit potential difference between the plates is called its capacity or capacitance. It is denoted by "C".
As Q= CV
If V=1 volt then C=Q
The capacitance 'C' depends on:
- a. The area of the plates
- b. The distance between the plates
- c. The medium between the plates.
Note that capacitance is always a positive quantity. The SI Unit of the capacitance is "Farad" after the scientist Michael Faraday.
The capacitance of a capacitor is said to be one farad if a charge of one coulomb, given to one of the plates, produces a potential difference of one volt between them. The farad is a very large unit. Its sub units are microfarad (10-6 farad) and pico farad (10-12 farad).
Combination of Capacitors:
Two or more capacitors are often connected in circuits in several ways. These capacitors can be combined either in series or in parallel circuits.
1. Series combination of Capacitors:
- 1When the capacitors are connected in series:the charge remains undivided, and the voltage or potential difference (P.D) is divided into parts, as shown in the figure.Advertisement
Consider two capacitors say "C1" & "C2" are joined to a battery of voltage "V". let "V1" & "V2" be the potential difference across each capacitor.
So V= V1+V2
Or Q/C= Q/C1 + Q/C2
So 1/C= 1/C1 + 1/C2
or 1/C= C1+C2/ C1C2
Where 'C' is the equivalent capacitance of the combination
Characteristics Features of Series Combination:
- 1There is only one path for the flow of charge in a series combination.
- 2The sum of the individual voltages is equal to the total voltage of the source.
- 3The reciprocal of equivalent capacitance is equal to the sum of the reciprocals of the individual capacitors.
2. Parallel Combination of Capacitors
Consider two capacitors "C1" & "C2" let the maximum charge on the two capacitors be represented by "Q1" and "Q2". Then
Q= Q1+Q2----------- (1)
As Q=CV > Q1= C1V & Q2= C2V
So Equation (1) > CV= C1V+C2V
> C= C1+C2 ------------ (2)
Where 'C' is the equivalent capacitance and C1,C2 are individuals capacitors. Now if there are n- number of capacitors, then
Characteristic features of Parallel capacitors:
- 1There are various paths for the flow of charges.
- 2The potential difference across each capacitor is the same, i.e V=V1=V2=V3=……
- 3The equivalent capacitance is equal to the sum of the individual capacitors.i.e Ceq= C1+C2+C3+………..+CnAdvertisement
Different Types of Capacitors:
Capacitors are of various types, sizes, and shapes. Generally, capacitors are of the following two types.
- 1. Fixed Capacitor:
A capacitor whose parts or components are fixed is called a fixed capacitor. E.g paper capacitors, mica capacitors etc.
"Construction" Paper capacitors consist of two aluminum foils between which greased paper or a plastic sheet is used as a dielectric. These are then rolled into a cylindrical shape.
- 2. Variable Capacitor:
The capacitor whose capacity can be changed by changing the area of the plates, or by changing the distance between the plates, is known as a variable capacitor. It is usually a combination of many capacitors, and the air is used as a dielectric. Variable capacitors are usually used in the circuits of radio tuning. By changing the capacity, different radio stations are tuned.
Referencing this Article
If you need to reference this article in your work, you can copy-paste the following depending on your required format:
APA (American Psychological Association)
Capacitors. (2017). In ScienceAid. Retrieved Mar 25, 2017, from https://scienceaid.net/Capacitors
MLA (Modern Language Association) "Capacitors." ScienceAid, scienceaid.net/Capacitors Accessed 25 Mar 2017.
Chicago / Turabian ScienceAid.net. "Capacitors." Accessed Mar 25, 2017. https://scienceaid.net/Capacitors.
Categories : Physics
Recent edits by: Sim