Georg Ohm

Electricity: Georg Ohm and Ohm's Law

A portrait of Georg Ohm
Wikimedia Commons / Public Domain

Georg Simon Ohm was born in 1787 in Erlangen, Germany. Ohm came from a Protestant family. His father, Johann Wolfgang Ohm, was a locksmith and his mother, Maria Elizabeth Beck, was the daughter of a tailor. Had Ohm's brothers and sisters all survived he would have been one of a large family but, as was common back then, several of the children died young. Only two of Georg's siblings survived, his brother Martin who went on to become a well-known mathematician, and his sister Elizabeth Barbara.

Although his parents had not been formally educated, Ohm's father was a remarkable man who had educated himself and was able to give his sons an excellent education through his own teachings.

Education and Early Work

In 1805, Ohm entered the University of Erlangen and received a doctorate and immediately joined the staff as a mathematics lecturer. After three semesters, Ohm gave up his university post. He could not see how he could attain a better status at Erlangen as prospects there were poor while he essentially lived in poverty in the lecturing post. The Bavarian government offered him a post as a teacher of mathematics and physics at a poor quality school in Bamberg and he took up the post there in January 1813.

Ohm wrote an elementary geometry book while teaching mathematics at several schools. Ohm began experimental work in a school physics laboratory after he had learned of the discovery of electromagnetism in 1820.

In two important papers in 1826, Ohm gave a mathematical description of conduction in circuits modeled on Fourier's study of heat conduction. These papers continue Ohm's deduction of results from experimental evidence and, particularly in the second, he was able to propose laws which went a long way to explaining results of others working on galvanic electricity.

Ohm's Law 

Using the results of his experiments, Ohm was able to define the fundamental relationship between voltage, current, and resistance. What is now known as Ohm's law appeared in his most famous work, a book published in 1827 that gave his complete theory of electricity.

The equation I = V/R is known as "Ohm’s Law". It states that the amount of steady current through a material is directly proportional to the voltage across the material divided by the electrical resistance of the material. The ohm (R), a unit of electrical resistance, is equal to that of a conductor in which a current (I) of one ampere is produced by a potential of one volt (V) across its terminals. These fundamental relationships represent the true beginning of electrical circuit analysis.

Current flows in an electric circuit in accordance with several definite laws. The basic law of current flow is Ohm's law. Ohm's law states that the amount of current flowing in a circuit made up of only resistors is related to the voltage on the circuit and the total resistance of the circuit. The law is usually expressed by the formula V= IR (described in the above paragraph), where I is the current in amperes, V is voltage (in volts), and R is the resistance in ohms.

The ohm, a unit of electrical resistance, is equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals.