Question

An air capacitor of capacitance $6\mu F$ is immersed in oil whose dielectric constant is $2.0$ . The capacitance of oil capacitor will be:
(A) $2.5\mu F$
(B) $8.5\mu F$
(C) $22\mu F$
(D) $12.0\mu F$

Answer 1

Hint : Capacitor is a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator. The Capacitance of a capacitor is the ratio of the amount of electric charge stored on a conductor to a difference in electric potential. The ratio in this case is the magnitude of the electric charge on either conductor and the potential difference is that measured between the two conductors.

Complete Step By Step Answer:
Air capacitors are capacitors which use air as their dielectric. The simplest air capacitors are made of two conductive plates separated by an air gap. Air capacitors can be made in a variable or fixed capacitance form.
Let ${C_c}$ and ${D_c}$ be the capacitance of a capacitor and the dielectric constant respectively. Also let $C$ be the amount of electric charge stored in an oil conductor.
Given ${C_c} = 6\mu F$ and Dielectric constant ${D_c} = 2.0$ .
Since, capacitance of a capacitor is the ratio of the amount of electric charge stored on a conductor to a dielectric constant.
$C = {C_c} \times {D_c} = 6 \times 2.0 = 12\mu F$
$\Rightarrow$ Oil capacitor will be $= 12\mu F$
Hence the correct option is D.

Note :
Dielectric constant is also called relative permittivity or specific inductive capacity. Capacitance is the amount of charge stored per unit volt. Dielectric is an insulating material. Dielectric strength is the maximum electric field above which an insulating material begins to break down and conduct.