Electricity has changed our world! Electric currents made it possible to create the internet and to lit up our nights! Our lives are completely dependent on electricity. But what is electric current?

You know that the world around us is made of atoms which are made up of electrons, neutrons and protons. Of the three, the electron and the proton are electrically charged. Electrons are negatively charged and protons positively, consider as -1 and +1.

Electric current actually consists of the motion of the electrons. The protons are tightly packed inside the nucleus of an atom whereas electrons are at the outer shells in the orbits around the nucleus. Since electrons are loosely held by the nucleus, they are able to travel freely within the limits of the body. This makes an electric current.

## Visualizing Electric Current

Imagine an iron beam with a rectangular cross section. Consider one single frame in this beam. Let’s visualize the flow of electrons inside the beam. Let’s consider the electron flow from the right to the left as \( Q_{negative} \) and flow from left to the right as \( Q_{positive} \). The total resultant electrical current through the frame in the time interval ‘t’ is \( Q_{net} = Q_{positive} – Q_{negative} \). Electric current is nothing net charge through the frame divided by the time interval.

\( I = \frac{Q_{net}}{t} \)Under normal conditions, the electrons are flowing haphazardly inside the body. So the total motions of the electrons through the frame cancel out since there are the same amount going in both directions. If the electric current comes out to be negative then it means that the current is flowing the opposite direction.

Watch this video to understand how current flows,

\(~~~~~~~~~~~~~~~\)

## Unit of Electric Current

So how do we measure electric current? The SI Unit is the Ampere, which is equivalent to a flow of one coulomb per second i.e 6.241 x 10^{18} charges, i.e electrons. If there are 6.241 x 10^{18} electrons flowing through our frame in one second then the electrical current flowing through it is ‘One Ampere.’ The current flowing through a typical lightening maybe tens or thousands of amperes and on the other end of the electromagnetic spectrum we have nerve impulses which are in the order of micro amperes.