Ohm's law is one of three fundamental laws which begin the study of electronics, in partnership with Kirchhoff's voltage and current laws. These three laws form the frame on which the rest of electronics is constructed. It's important to note that these laws don't apply everywhere, but definitely apply with great precision in wires, which are used to connect most electronic parts together in a circuit. Though individual parts may or may not be analysed by Ohm's law, their relationship to the circuit can be. Any student completing a course in electronics should be capable of quoting Ohm's law in his or her sleep. Not because they learn it once, but because it's used repeatedly in conjunction with almost every other task in electronics.
The actual statement of Ohm's Law is: The current flowing through a metallic conductor is proportional to the Electromotive force applied across it's ends, provided the temperature and all other conditions remain constant.
The law was named after Georg Simon Ohm (16 March 1789 – 6 July 1854) was a German physicist published it in 1827. As a high school teacher, Ohm began his research with the recently invented electrochemical cell, invented by Italian Count Alessandro Volta. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential difference (voltage) applied across a conductor and the resultant electric current. This relationship is now known as Ohm's law.
Ohm's law applies to electrical circuits; it states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them.
The mathematical equation that describes this relationship is:
where V is the potential difference measured across the resistance in units of volts; I is the current through the resistance in units of amperes and R is the resistance of the conductor in units of ohms.
As a Pie Chart
To use pie chart, you can calculate E, I, or R measurements. In order to calculate 'E', first cover with your index finger the letter 'E' on the pie chart. Next, look at the two letters remaining that are 'I' and 'R'. If you closely observe both 'I' and 'R' are next to each other or as in algebra 'I' is multiplied by 'R'.
Conversely, to calculate 'I' or 'R', first cover with your index finger the letter 'I' on the pie chart. Next, look at the two letters remaining that are 'E' and 'R'. If you closely observe both 'I' and 'R' are above each other or as in algebra 'E' is divided by 'R'