Question

Give the reason why a dielectric material increases capacitance compared with what it would be with air between the plates of a capacitor. What is the independent reason that a dielectric material also allows a greater voltage to be applied to a capacitor? (The dielectric thus increases \(C\) and permits a greater \(V\).

Short answer

A dielectric material becomes polarised and develops parallel plates which as a result causes increased capacitance due to insulator’s polarisation.

Step-by-step solution

Defining Capacitance

Capacitance is the property of a component or circuit to accumulate and hold energy in the form of an electrical charge. There are many different shapes and sizes of capacitors, which are energy storage devices.

The reason of why a dielectric material increases capacitance

When an electric field is supplied to a dielectric that is sandwiched between the capacitor's plates, the material will become polarised. As a result, a dipole moment develops between a capacitor's parallel plates. A parallel plate capacitor's increased capacitance is caused by the insulator's polarisation. Its dielectric constant,\(k\), increases with ease of polarisation. The charged plates of a capacitor cause the molecules in the insulating material between the plates to become polarised. This causes a layer of opposing charge to form on the dielectric's surface, which draws additional charge to the plate and raises its capacitance.

More voltage can be provided in order to maintain a consistent ratio of \(C,\left( {C = \frac{Q}{V}} \right)\) because the dielectric material raises the charge on the capacitor's plates. (For instance, if \(C\) were \(\frac{{1{\rm{ }}mC}}{{1{\rm{ }}V}}\) and the dielectric permitted it to boost the charge to \(2{\rm{ }}mC\), the voltage could be \(2{\rm{ }}V\).)