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Dielectrics and Capacitance
Dielectrics and capacitance are two concepts with different functions and significance. They are introductory physics concepts that provide the foundation for understanding the electric charge distribution in dielectrics and their effect on capacitors. Dielectrics are materials placed between the plates of a capacitor, which allow for the storage of electrical energy. Electrical fields act on both polarisable and non-polarising materials. They provide an electrical insulator to minimise current leakage while causing a dielectric to an electrical dipole. As a result, all charges cannot be polarised against each other as they usually would be when pulled by an external field (QED).
What are dielectrics?
Dielectrics are materials that are placed in between the plates of a capacitor. Dielectric polarisation is the term used to describe the behaviour of a material when an external electric field is applied to it. Dielectric polarisation is the development of a dipole moment in an insulating material as a result of an externally applied electric field.
Dielectrics have the following three properties:
1) Polarisation: This is the condition of a dipole moment being induced in the molecule.
2) Dissipative: Also known as polarisable materials or dielectrics materials that can store energy within their polarisation.
3) Non-polarisable materials: Non-polarisable materials are materials that do not possess a dipole moment and cannot store energy.
The concept of polarisation is the direct result of the presence of an electric field applied to a dielectric material. This phenomenon provides the foundation for understanding the electric charge distribution in dielectrics and their effect on capacitors. They are often referred to as an insulator as it prevents electricity from leaking through, creating a polarised dielectric with no charge.
What is capacitance?
Capacitance is the measure of a capacitor’s ability to store electrical energy. It is also the ratio of the voltage applied to stored energy. Capacitance also produces electric fields all over the capacitor but are significantly weaker than those made by conductors’ charges. Also, the electric field is approximately uniform inside a dielectric. Capacitors are devices that store electricity by storing amounts between their plates. The current flow through the capacitor is directly proportional to the voltage applied and inversely proportional to its capacitance within a specific frequency range.
Significance of dielectrics and capacitance
To understand the significance of dielectrics and capacitance, one must realise that both types of materials interact with electric fields existing in surrounding materials. This provides a mechanism for storing energy in dielectrics and increasing the capacitance of capacitors.
The applications of capacitors are many, and they are ubiquitous throughout numerous areas of technology.
1) They can be used to measure electric fields. This is done by measuring the charge that a material stores – its capacitance.
2) They are used in many electrical circuits as components because they can store charge.
3) Capacitors can also determine a material’s properties based on its capacitance.
Differences between dielectrics and capacitance
Dielectrics | Capacitance |
They are materials placed in between the plates of a capacitor. When exposed to an external electric field, it causes a dielectric material to produce a dipole. | Capacitance measures a capacitor’s ability to store electrical energy. It is also the ratio of the voltage applied to stored energy; Capacitance also produces electric fields all over the capacitor but are significantly weaker than those made by charges on conductors. Also, the electric field is approximately uniform inside a dielectric. |
Dielectrics conduct electricity. So, while dielectrics can be used to reduce the voltage across a device, they do not transfer energy when switched on. | Capacitors do not conduct electricity. They are devices that store electricity by storing charges between their plates. |
Dielectrics can be measured by its capacitance. | Capacitance requires some type of dielectric material |
Dielectrics are ubiquitous throughout technology. They provide electrical insulators that decrease current leakage and cause polarised dielectrics, which can be used as components in many circuits. | Capacitors produce electric fields with charges in which they accumulate. |
Dielectrics can be used to reduce the voltage across a device. | Capacitors do not transfer energy when switched on. |
Conclusion
Dielectrics and capacitors have different functions and significant roles in many technology and sciences fields. Both can store energy in a form used for other applications. Through the capabilities of dielectrics, capacitors can store charge, which is demonstrated by their large capacity and their ability to store more significant amounts of electrical energy than conductors. The significance of the concept of dielectrics and capacitors is that it provides a basic understanding of how dielectrics work and how capacitors work.
