Insight to capacitors
Insight to capacitors
Capacitance is the measure of charge storage capability of an element. The capacitor is an element generally employed in the electric circuit for storing some electric charges. The charge storage in the capacitor is directly proportional to the potential difference across the leads of the capacitor.
Insight to the capacitor the dielectric material and its strength can be quantified in terms of the permittivity (ε) also defined as the measure of the capacitance of the material or medium. Based on the geometry the capacitors can be classified into three type’s parallel plate, spherical and cylindrical whose capacitances are tabulated in table 1. The capacitance of the basic geometry of the capacitors i.e. parallel plate capacitor depicted in table 1, C= A ε/d where ‘A’ is the cross-sectional area of the plates and’ denotes the separation between the plates. Let us assume the capacitor with the unit area and unit distance of separation then the capacitance of the capacitor C= ε. Where ε= εo εr where εo is the permittivity of the air which is constant and εr is the relative dielectric constant which varies with respect to the material chosen. So from the above it can clearly understand that C α εr, in other words, the capacitance of the capacitor solely depends on the relative dielectric constant of the material chosen.
Table 1
Type of the capacitor | Geometry | The capacitance of the capacitor |
1.Parallel plate | A ε/d | |
2.Spherical | (4 π ε R1R2)/ (R2– R1) | |
3.Cylindrical | 2 π ε/ln(R2/ R1) |
Energy storage:
The energy stored in any element can be estimated if power dissipation across it is known. As the rate of work done is nothing but power.
P=dE/dt
E= ∫P dt
So for a capacitor, the energy stored can be estimated as E= 0.5 CV2.
The capacitance of all these capacitors primarily depends on the dielectric material used in it. The higher the dielectric strength higher is the capacitance of that particular capacitor. Different types of capacitors by their names are available in the market viz. film capacitor, ceramic capacitors, and electrolytic capacitors etc.
- Film capacitor:
Film capacitors are available as shown in the figure below. These capacitors are prominent in high voltage storage. The range value of the capacitance for the film capacitor can be as high as 1500 volts because of their exceptional dielectric properties. The electrodes of film capacitors are made up of zinc or aluminium and dielectric material used for film capacitor is polystyrene, polycarbonate or Teflon for which these capacitors can also be called as plastic capacitors. These capacitors can be employed in class-1 frequency-stable operations. One such film capacitor is shown below.
- Ceramic capacitor:
The other common name of the ceramic capacitor as the name indicates ceramic capacitor the dielectric material used in this is ceramic and possess a high dielectric constant of ranges from 7000 to 9000. This capacitor is, in general, a fixed value capacitor used in high-frequency application i.e. from audio to RF. The loss in this type of capacitors is significantly less with a dissipation factor of less than 2.5%. The capacitance value of the ceramic capacitors can be varied based on the thickness of the ceramic disc. The fabricated usage ready ceramic capacitor is shown below.
- Electrolytic capacitors
The oxide layer used as a dielectric material for the electrolytic capacitors. The metal is used for anode or positive plate where the solid, liquid or gel-type electrolyte can be used as a cathode or a negative plate of the capacitor. As the oxide layer is very thin the capacitance value up to 500 volts. These capacitors are not available at a higher temperature and higher voltage values. The commonly used anode material for electrolytic capacitors is aluminium, tantalum or niobium.
- Supercapacitor
These are a special type of capacitors possess a substantially higher amount of capacitance compared to the ordinary capacitors. The other name given for these capacitors is ultra-capacitors. These capacitors generally made up of versions of carbon material. These materials shall be employed where there is a requirement of rapid charging and discharging. The picture of the supercapacitor those are available in the market shown below.
Conclusion:
Through the above different varieties of the capacitors and insight to it is understood.
image source
- 1-tab: https://en.wikipedia.org/wiki/Capacitance
- 2-tab: https://en.wikipedia.org/wiki/Capacitance
- 3-tab: https://en.wikipedia.org/wiki/Capacitance
- 4-: https://www.digikey.in/product-detail/en/nichicon/LGU2E681MELB/493-2771-ND/1004432?cur=INR&lang=en&utm_adgroup=Aluminum%20Electrolytic%20Capacitors&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Capacitors&utm_term=&productid=1004432&gclid=EAIaIQobChMI2Lyqi5bP6gIVyhErCh2kMw5KEAQYBCABEgJK3fD_BwE
- 5: https://www.digikey.in/product-detail/en/nichicon/LGU2E681MELB/493-2771-ND/1004432?cur=INR&lang=en&utm_adgroup=Aluminum%20Electrolytic%20Capacitors&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Capacitors&utm_term=&productid=1004432&gclid=EAIaIQobChMI2Lyqi5bP6gIVyhErCh2kMw5KEAQYBCABEgJK3fD_BwE
- 6: https://www.elprocus.com/capacitors-types-applications/
- 7: https://www.digikey.in/product-detail/en/nichicon/LGU2E681MELB/493-2771-ND/1004432?cur=INR&lang=en&utm_adgroup=Aluminum%20Electrolytic%20Capacitors&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Capacitors&utm_term=&productid=1004432&gclid=EAIaIQobChMI2Lyqi5bP6gIVyhErCh2kMw5KEAQYBCABEgJK3fD_BwE
- Featured: https://phys.libretexts.org/Bookshelves/University_Physics/Book%3A_University_Physics_(OpenStax)/Map%3A_University_Physics_II_-_Thermodynamics%2C_Electricity%2C_and_Magnetism_(OpenStax)/08%3A_Capacitance/8.02%3A_Capacitors_and_Capacitance