Question

What is the resistance of an air gap?

Answer 1

To answer this question, we should know that an air gap is considered to be a completely insulating material. By an insulator we mean that it will not allow the passage of electricity through it.

Complete step by step answer:
We should know that an electric current flows whenever there are electrons moving through a conductor. While the movement when the free electrons clash or we can say collide with the ions that are present in the metal. This interrupts the flow of the free electrons and also the current flow is interrupted. This is how the resistance is caused.

The electrical resistance that is offered by an air gap is considered to be very high. The value is almost equal to $\approx {{10}^{9}}\Omega m$. By this we mean that for per metre distance the resistance offered will be ${{10}^{9}}$by the air gap. This happens because of the presence of the molecules of elements like oxygen and nitrogen. There is the presence of no free electrons in the air gap.

But we should know that if we apply very high potential then the air can get ionized and then it will start to conduct electricity, or we can say it will start becoming conducting. The value of the potential gradient will be $3\times {{10}^{6}}V/m$.

Note: In the answer we have come across the term free electrons. By free electrons we mean that those electrons will be attached to the ions, atoms or molecules and whenever there is the influence of any externally applied electric or magnetic field then these electrons eject from the surfaces, thus conducting the current. The free electrons have very low kinetic energy and they have active participation in the various thermal motions of all the atoms.