Ohm`s Law

We now know what is Electricity and also what is Current, And what is voltage!
The next step we are about now is our first step in electronics field to control that energy.

in January 1781,  Henry Cavendish was experimenting The current with Leyden jars  Using glass tubes of varying diameter and length filled with salt solution.
He was measuring the current by noting how strong a shock he felt as he completed the circuit with his body.

Georg Ohm starts his work on resistance in 1825, He drew considerable inspiration from Fourier`s work on heat conduction in the theoretical explanation of his work.

At first, he used Voltaic piles but later he used a galvanometer to measure the current, He added test wires of varying length, diameter, and material to complete the circuit, He founded that his data could be modeled through the equation      

x ==> galvanometer readings

l ==> length of the conductor

a ==> depended only on the thermocouple junction temperature

b ==> constant of the setup

and this was this was determining of his law of proportionality then he published his results.

Now after developing many of the materials and understanding the characteristics of most of them we have :

Resistors [which equivalent to] l ==> length of the conductor

So now Ohm`s law states that the current through a conductor between two points is directly proportional to the voltage across the two points,

Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship:

       I=V/R,

I ==> the current through the conductor in units of Amperes

V==> the voltage measured across the conductor in units of Volts

R==> the resistance of the conductor in units of Ohms