Ohm's law describes the relationship between voltage, current, and resistance in an electrical circuit as V = IR.Georg Ohm in 1826 experimentally investigated how metals conduct electricity. At that time, it was believed that current is a flow of a mysterious fluid. Ohm established a clear mathematical relationship: current I = U / R, where R is a characteristic of the conductor. He presented the result in the book 'The Galvanic Circuit Investigated Mathematically', but colleagues received the work coldly. Recognition came only a few years later. Today Ohm's law is the ABC of electrical engineering: in any microchip, transformer, LED strip, it is essential.
Georg Simon Ohm, a German physicist, in 1825–1826 conducted a series of meticulous experiments with galvanic cells and metal wires of different lengths and cross-sections. Using a modified Coulomb torsion balance to measure current, he discovered a linear dependence. In 1827, his book 'Die galvanische Kette, mathematisch bearbeitet' was published, where he introduced the concepts of electromotive force, current strength, and resistance. Contemporaries, including Georg Hegel, mocked the 'useless fantasies', but by the 1840s the law gained universal recognition. James Clerk Maxwell later integrated it into the unified theory of electromagnetism.
Ohm's law forms the basis of analyzing electrical circuits — from household appliances to superconducting magnets. Its limits: materials with a nonlinear current-voltage characteristic (semiconductors, diodes, gas discharges) do not obey simple proportionality. Also, at high frequencies or temperatures near absolute zero, effects appear that require quantum corrections.
In any electrical device, the calculation of the resistance of a heating element or fuse uses Ohm's law. Without it, you cannot adjust speaker volume or select wire gauge for wiring.
The human body is a conductor. The resistance of dry skin is ~100 kΩ, while wet skin drops to 1 kΩ. The danger of electric shock increases dramatically after a shower.
| σ | variable | Ohmic conductivity — electrical conductivity siemens per metre |
