Question

The dielectric constant for a metal is:
A. zero
B. infinite
C. $1$
D. $10$

Answer 1

Dielectric constant is the ratio between the electric permeability of a material to the electric permeability of free space or vacuum. It is the ability of a material to resist the creation of an electric field within it. Remembering these points and the basic properties of metals will help the students to approach the answer.

Complete step by step answer:
Being the ratio between the permeability or the permittivity of a substance to that of the free space, dielectric constants of metals have a very large value. The permittivity of metals always exceeds the value of the permittivity of the free space. This is because the constant measures the resistance capacity of a metal towards building an electric field within it. As the value of the electrical flux density of the material increases, the value of the dielectric constant also increases. This leads to the value of the net electric field inside the metal to become zero. This implies that the metal must take up an infinitely large value to resist the formation of an electric field within it.Thus we can conclude that the dielectric constant for metals is infinite.

Hence, we can say that option B is the correct answer.

Note: The dielectric constant can also be defined in terms of a capacitor as the ratio of its capacitance when the plates are filled by the medium, to the capacitance when there is air in between the plates. This method can also be used to calculate the dielectric constant.