Question

What do you mean by Electric Flux? Write its SI unit.

Answer 1

Hint: We will first discuss the electric field through a given area or the electric field lines through a given virtual surface. Electric field simply means the region where a force is exerted on a charged body when it’s around another charged body or particle. After knowing about the electric field, we can talk about the electric flux.

Complete step-by-step answer:

Let us assume the case when water is flowing through a pipe in a given direction like say right with some velocity say ‘v’. If we take cross-section of the pipe and consider the small unit area of the cross-section to be $ds$ then the flow of the water flowing through plane in normal direction will be $vds.$ In case plane is inclined at some sort of angle say $\theta $ then the flow of the water flowing through plane inclined at some angle $\theta $ will be $vds\cos \theta ,$ where $ds\cos \theta $ is the area in the plane that is at right angle to the water flow.

We can relate our Electric field to the flow of water.

Hence, we can say that the Electric flux is defined as the total number of electric field lines that are passing through a given area in a unit time. When plane is inclined at an angle $\theta $ to the electric field lines then the total flux is given by $\phi = EA\cos \theta $ where E is the magnitude of the electric field, A is the area of the plane surface and $\theta $ is the angle at which the plane is inclined to the electric field lines.

SI unit of Electric Flux: SI unit is the standard unit of measurement that is defined by the International System of Units. Now, talking about the SI unit of electric flux, we know that Electric flux consists of the Electric field and the area of the plane. So, SI unit of electric flux should be newton-meters squared per coulomb $\left( {N{m^2}{C^{ - 1}}} \right)$ or volt meters $\left( {Vm} \right).$

Note: We can just say that the electric flux is nothing just the measure of the distribution of electric field through an area. Electric flux is just used to tell the electric field strength at any distance from the charge that is responsible for the field.