Math & science · 1820

Current deflects a compass

Oersted notices an electric current swinging a compass needle.

The first link between electricity and magnetism was followed within weeks by Ampere's force law. It made the electromagnet, the telegraph and the motor possible.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

Voltaic battery 1800
De Magnete 1600

What it led to 1

Electromagnetic induction 1831

Related measurements

The dashed line marks when it first worked.

Telegrams sent in the UK Latest: 5.7M telegrams per year (1983) Source: Our World in Data