Question

Capacity of a parallel capacitor with dielectric constant $5$ is $40\mu F$.Calculate the capacity of the same capacitor when dielectric material is removed.

Answer 1

Hint:To calculate the capacity of the capacitor, we use the concept of capacitor with and without dielectric and the effect of dielectric on the capacity of the capacitor. We will also discuss dielectric used in capacitors that increases the storage capacity of the capacitor.

Formulae used:
The capacity of parallel plate capacitor with dielectric is given by
${C_d} = k{C_{air}}$
Where, $k$ - dielectric constant and ${C_{air}}$ - capacity of parallel plate capacitor with air as dielectric.

Complete step by step answer:
Parallel Plate Capacitors are formed by an arrangement of electrodes and insulating material or dielectric. A parallel plate capacitor can only store a finite amount of energy before dielectric breakdown occurs. Given, $k = 5$ , ${C_d} = 40\mu F$
Using the given formula,
${C_d} = k{C_{air}}$
$\Rightarrow 40 = 5{C_{air}}$
Solving, we get
$\therefore {C_{air}} = 8\mu F$

Hence, the capacity of the same capacitor when dielectric material is removed i.e. air as dielectric is ${C_{air}} = 8\mu F$.

Note: The capacity of a parallel plate capacitor with dielectric constant $k$ is, dielectric constant times the capacity of a parallel plate capacitor with air as dielectric.Dielectric is an insulating material having properties of charge storage having properties of charge storage which increases the capacity of the capacitor.