Also known as: Georg Ohm, Georg Simon Ohm, Ohm
Georg Ohm (1789–1854) was a German physicist who discovered the simple proportional relationship between the voltage across a conductor and the current through it — the law that carries his name, V = I·R.1 The relation is the most basic tool in all of electronics, and its alternating-current generalization to complex impedance governs every RF matching network and filter.
Life and work
Georg Simon Ohm was born in Erlangen, Bavaria, and worked for years as a schoolteacher while pursuing physics research, often with apparatus he built himself. In 1827 he published Die galvanische Kette, mathematisch bearbeitet (“The Galvanic Circuit Investigated Mathematically”), stating the proportional law between potential difference and current. The work was poorly received at first — some German academics found its mathematical style unwelcome — and recognition came only slowly.1
Ohm was eventually vindicated: the Royal Society awarded him the Copley Medal in 1841, and late in life he obtained a professorship at the University of Munich. The ohm, the SI unit of electrical resistance, is named in his honour.
Contribution
Ohm’s law states that, for a metallic conductor at constant temperature, the current is directly proportional to the applied voltage, with resistance as the constant of proportionality:
- V = I·R — voltage equals current times resistance.
Though elementary, it is the starting point for circuit analysis. Combined with the conservation laws of Gustav Kirchhoff, it lets any resistive network be solved. Extended to alternating current, resistance becomes complex impedance, which describes how capacitors and inductors respond to frequency and thus how tuned circuits reach resonance — the everyday arithmetic of filters, attenuators, and the decibel power relations used throughout RF work.
Legacy
Ohm’s law is the first equation of electronics, quietly present in every resistor value, every bias calculation, and every impedance match. It provided the empirical footing that the later field theory of James Clerk Maxwell built upon, and it remains indispensable in the design of the analog front end of any software-defined radio.