Barlow’s Law: The Wire Scaling Rule That Failed #Shorts

Added: 2026-05-05

[00:00:00]Picture a wire, then change only its length, and the effect should follow a neat rule.

[00:00:04]But in 1825, Peter Barlow's formula was incorrect. Barlow proposed how electricity affects scale with wire size. He claimed the effect varies inversely with the square root of length.

[00:00:15]He also claimed it varies directly with the square root of cross-sectional area.

[00:00:19]Engineers later learned the rule was just wrong. That matters because it sounds almost right, like a practical shortcut.

[00:00:25]Yet Barlow's law is classified as an incorrect physical law. So, the next time you see a simple scaling formula, remember 1825.

[00:00:33]A wire can trick you, even when the math looks confident.