b) what is the relationship of structure to the dielectric properties of the material
A typical capacitor comprises two conductive plates and a non-conductive dielectric material. The dielectric cloth separates the two conductive metal electrode plates. Applying voltage to the electrode plates of a capacitor causes an electric field in the not-conductive dielectric material. This electric field stores energy. The dielectric constant, also commonly known as relative permittivity, is the measure of the ability of a fabric to store electric free energy, and is one of the key properties of a dielectric material.
The capacitance of a parallel plate capacitor is a function of altitude between plates, plate area, and dielectric textile constant. An increment in plate area and dielectric constant results in an increase in capacitance while an increase in the separation distance between the plates results in a decrease in capacitance. Different dielectric materials have different dielectric constants.
Effects of dielectric abiding on the characteristics of a capacitor
The dielectric textile of a capacitor polarizes when voltage is applied. This process reduces the electric field and causes negatively charged electrons to shift slightly towards the positive concluding. Although the electrons practice not shift far enough to cause a flow of current, the procedure creates an effect that is critical to the operation of capacitors. Removing the source of voltage causes the dielectric textile to lose polarization. However, if the fabric has weak molecular bonds, it can remain in polarized state fifty-fifty when the source of voltage is removed.
A capacitor stores energy in the electric field when a voltage is applied. The chapters to store electrical free energy varies from one dielectric material to another. The amount of electrical energy that a capacitor tin can store is influenced by the corporeality of polarization that occurs when voltage is practical. Materials with high dielectric constants tin store more than energy compared to those with low dielectric constants. The electric susceptibility of a material is a measure of the ease with which it polarizes in response to an electric field. Proficient dielectric materials have high electric susceptibility.
The dielectric constant is 1 of the fundamental parameters to consider when selecting a dielectric material for a capacitor. This abiding is measured in farads per meter and determines the amount of capacitance that a capacitor can achieve. Dielectric materials with high dielectric constants are used when high capacitance values are required, although, equally mentioned above, other parameters that determine the capacitance of a capacitor include the spacing between the electrodes and the effective plate expanse.
Dielectric constants of common dielectric materials
All materials are capable of storing electrical free energy when they are exposed to an electric field. The storage capacity varies from one textile to another. The permittivity of materials is usually given relative to the permittivity of costless infinite, unremarkably symbolized by ϵ0. The permittivity of vacuum is unremarkably known as absolute permittivity and refers to the amount of resistance required to class an electric field in a vacuum. The absolute permittivity of free infinite is approximately 8.85418782 × 10-12 g-3 kg-1 s4 A2.
The permittivity of a dielectric material relative to that of free space is referred to as relative permittivity, unremarkably symbolized past ϵr, or dielectric constant. The following equation relates absolute permittivity (ϵ0), relative permittivity or dielectric constant (ϵr), and permittivity of a fabric (ϵ).
ϵr=ϵϵ0
The tabular array below shows the dielectric constants of commonly used dielectric materials.
There are many other materials with dielectric properties, overview of dielectric constant on wide range of organic plastic materials is provided in the article here.
Variations in temperature cause discontinuities in the permittivity of a dielectric material, and have a pregnant issue on the dielectric constant of a material. For example, an increase in temperature causes a decrease in permittivity, and the dielectric abiding of a cloth drops sharply when the temperature falls beneath the freezing bespeak.
When selecting a dielectric textile for a capacitor, it is also of import to consider the effect of frequency on the material's properties. The permittivity that a material exhibits when information technology is exposed to an electric field is dependent on the frequency of the voltage source. When a material is placed in a static electrical field, the permittivity that it exhibits is referred to every bit static permittivity. The permittivity of a textile decreases with an increase in frequency of the voltage source.
A primary bulldoze today is towards circuit miniaturisation. To produce miniature circuits components with a smaller footprint are required. The dielectric constant of a capacitor determines the capacitance that tin be achieved. Dielectric materials with loftier dielectric constants are used when capacitors with smaller concrete sizes are required.
Apart from dielectric constant, it is besides of import to consider dielectric loss and dielectric force when selecting a dielectric textile for a capacitor. The dielectric strength is a measure of the voltage that an insulator will withstand before information technology allows current to flow through information technology. The dielectric loss refers to the free energy that a dielectric material dissipates when a variable voltage is practical.
Determination
A dielectric fabric is used to carve up the conductive plates of a capacitor. This insulating textile significantly determines the backdrop of a component. The dielectric abiding of a cloth determines the amount of energy that a capacitor tin store when voltage is applied. A dielectric material becomes polarized when information technology is exposed to an electrical field. When polarization occurs, the effective electric field is reduced. Since the permittivity of a textile is dependent on frequency and temperature, the dielectric constant is usually given at specific atmospheric condition, usually at depression frequencies. Moreover, the dielectric constant of a material is usually given relative to the permittivity of free space.
Source: https://passive-components.eu/the-dielectric-constant-and-its-effects-on-the-properties-of-a-capacitor/
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