GEORG SIMON OHM (1787-1854), German physicist, was born at Erlangen on the 16th of March 1787, and was educated at the university there.
For this purpose a resistance, say, of one ohm is placed in series with the lamp and a resistance of 100,000 ohms placed across the terminals of the lamp; the latter resistance is divided into two parts, one consisting of loon ohms and the other of 99,000 ohms. The potentiometer enables us to measure therefore the current through the lamp by measuring the drop in volts down a resistance in series with it and the potential difference of the terminals of the lamp by measuring the drop in volts down the tooth part of the high resistance of 100,000 ohms connected across the terminals of the lamp.
In Germany the work of Martin Ohm (System der Mathematik, 1822) marks a step forward.
His data for the thermal conductivity of various metals were for long the most trustworthy at the disposal of physicists, and his determination of the ohm in terms of the specific resistance of mercury showed remarkable skill in quantitative research.
He followed up the early work of the British Association Committee on electrical units by a fresh determination of the ohm in absolute measure, and in conjunction with other work on the electrochemical equivalent of silver and the absolute electromotive force of the Clark cell may be said to have placed exact electrical measurement on a new basis.
Volta) is defined to be difference of potential which acting between the terminals of a resistance of one ohm sends through it a continuous current of one ampere.