Barlow's law

Barlow's law was an incorrect physical law proposed by Peter Barlow in 1824 to describe the ability of wires to conduct electricity.^[1] It said that the conductance of a wire varies inversely with the square root of its length and directly with the square root of its cross-sectional area, or:

where G is conductance, l is the length of the wire, A is the cross-sectional area of the wire, and k is a constant specific to the material of the wire.

In 1827, Georg Ohm proposed an opposing law, stating that the resistance of a wire varies directly with its length and inversely with its cross-sectional area. Experiments eventually proved Ohm's law correct and Barlow's false.

Barlow undertook his experiments with the aim of determining whether long-distance telegraphy was feasible, and believed he proved that it was not.^[2] The publication of Barlow's law delayed research into telegraphy for several years, until Joseph Henry and Philip Ten Eyck disproved it in 1831.

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