Dielectric Constant Class 12

Dielectric Constant

    Those non-conducting substances are called dielectrics in which they get polarized when an electric field is applied inside them. Non-conductors refer to all those substances which have high resistivity, but dielectric substances are those which, along with being non-conductors, also exhibit the property of polarization in sufficient quantity.

What Is the Dielectric Constant?

Dielectric Constant

    The ratio of the permittivity of a medium to the permittivity of air or vacuum is called the relative permittivity of that medium. Earlier it was called 'dielectric constant' but now the standards bodies have given up this term. That is, `\epsilon_r = \frac{\epsilon}{epsilon_0}`

Dielectric Constant Formula

`\epsilon_r = \frac{\epsilon}{epsilon_0}`

Where,

`\epsilon_r` is the dielectric constant

𝜺 is the permittivity of the substance

`\epsilon_0` is the permittivity of the free space

Dielectric Constant Units

As it is the ratio of two like entities, Dielectric Constant is a unitless, dimensionless quantity because it is the ratio of two like entities.

Dielectric Constant Symbol

    The ratio of the permittivity of a medium to the permittivity of air or vacuum is called the relative permittivity of that medium. Earlier it was called 'dielectric constant'. It is represented by `\epsilon_r` or k.

Dielectric Constant Value

Dielectric constant for a metal is infinite.

Dielectric constant of water is 81.

Dielectric constant of air at room temperature is 1.00059 .

Dielectric constant of glass is 5 to 10.

Dielectric constant of Mica is 3 to 6.

Dielectric constant of Paraffin wax is 2 to 2.5.

Dielectric constant of Vacuum is 1.

Dielectric constant of glycerin is 42.5.

Dielectric constant of rubber is 7.

Dielectric constant of Oxygen is 1.00053.

Questions and Answers

What is a dielectric?

    Dielectrics are non-conducting substances that get polarized when an electric field is applied to them.

How is a dielectric different from a regular non-conductor?

    Dielectrics exhibit the property of polarization in sufficient quantity in electric field while both have high resistivity.

What is the dielectric constant?

    The dielectric constant is the ratio of the permittivity of a medium to the permittivity of air of vacuum. It is also known as relative permittivity.

What is the formula of the dielectric constant?

The formula of the dielectric constant is -

`\epsilon_r = \frac{\epsilon}{\epsilon_0}`

`\epsilon_r ` = Relative permittivity.

`\epsilon` = Permittivity of the substance.

`\epsilon_0` = Permittivity of free space.

What are the units of the dielectric constant?

    The dielectric constant is a unitless and dimensionless quantity because it is a ratio of two like entities.

What is the dielectric constant value for metal?

    The dielectric constant for a metal is infinite.

What is the dielectric constant of water?

    The dielectric constant of water is 81.