Hans Christian Oersted

- the man who discovered electromagnetism

In these early days of electricity, the facts that we take for granted were not known and it took great men like Hans Christian Oersted to discover them.

Early career
Born in 1777, Hans Christian Oersted was the son of a Danish Apothecary, and in his early childhood he and his brother were looked after by neighbours whilst his parents worked in their business. These neighbours provided him with an education.

Oersted then served an apprenticeship in his father's apothecary and then both he and his brother studied at Copenhagen University. Hans Christian studied Chemistry and his bother studied law. In fact his brother rose through the judiciary and eventually became prime minister.

Oersted gained a Ph.D. and continued to study philosophy. However to earn a living he worked at an apothecary whilst acting as a part time unpaid lecturer at the university. This lead to an award of a three year travel scholarship that took him around Europe and it enabled him to follow up on his scientific interests.

On returning to Copenhagen, Hans Christian Oersted could not gain the professorial position he wanted as a result of some ill-thought-out statements he had made which were criticised by leading scientists. Fortunately some popular lectures Oersted gave on various scientific topics helped restore his reputation and he secured a post as an "extraordinary professor".

Initial theories
As a result of his studies in philosophy, Oersted had thought that there were links between the different forces in nature. Already the new science associated with electricity had demonstrated there was a link between electricity and chemistry as a result of Volta's work on cells. If this was try then why not between electricity and magnetism? In 1812-1813, Oersted expressed these ideas in a book, despite the fact that it did not fit in with the thinking of the time.

Discovery made
In the winter of 1819-1820, Hans Christian Oersted gave a number of lectures on electricity and magnetism to a small group of advanced students. One that he wanted to try was the effect of a closed electrical circuit (i.e. with a current flowing) on a magnetised needle. Unfortunately he did not have time to try it before the lecture, and decided to postpone it. However during the lecture he changed his mind and tried it. Despite the fact that the wire was thin and the resistance high, a sufficient current flowed to deflect the needle - his theories had been proved.

Further experiments were needed because the effect was not particularly dramatics, but they had to be postponed for three months until a more powerful battery and thicker wire were available.

Once these were available Oersted performed the experiment again, and also looked more into its nature checking that it was not an electrostatic effect.

Oersted published his findings and circulated them to many leading scientists in Europe. The paper created an enormous response as people realised the significance of the discovery.

Later Life
Oersted continued a variety of scientific researches. Much of his later work involved studies of the compressibility of gases, and beyond this he turned back to his first love - philosophy before his death in 1851.