Who discovered the Electromagnetic Effects

Hans Christian Oersted’s Electromagnetic Effects. Oersted Discovers Electric Currents Induce Magnetic Fields. During a class, Oersted noticed that a compass near a wire carrying electricity was affected by the current induced magnetic field.

Electric and Magnetic Phenomena

We now know that electrical and magnetic phenomena are intimately connected. They can not be separated. However physicists did not always know that electricity and magnetism were interconnected.

In the early 19th century physicists were beginning to suspect that electric and magnetic phenomena were related, but had not yet found the connection. One of the physicists seeking this connection was Hans Christian Oersted (1777 – 1851). Oersted was a Danish physics professor at Copenhagen University, who discovered the connection quite unexpectedly.

Oersted’s Discovery

On July 21, 1820 professor Oersted was teaching his students a class on electricity. He had prepared an electrical demonstration for his students, which involved a wire connected to a battery. By chance a magnetic compass was lying on the table near the wire. It was not part of Oersted’s electrical demonstration and apparently had been left on the table with other random pieces of equipment. What followed is a good example of a payoff for not being obsessively neat in a laboratory.

The stage was set. Oersted had been looking for a connection between electric and magnetic effects. An electricity demonstration was ready for his class. A magnetic compass was lying in a random pile of equipment near the electrical wire.

Oersted closed the switch. The electric current flowed through the wire powering his electricity demonstration. Totally unexpectedly, the compass needle jumped. It no longer pointed north under the influence of Earth’s magnetic field. It was apparently under the influence of another magnetic field.

A lesser intellect might have wondered why the compass was jumping around and then forgotten about it. If Oersted’s mind had not been primed by searching for a connection between electric and magnetic phenomena, he might not have made the connection. If someone had cleaned up the lab and put the compass in its proper location, it would not have been there to suddenly jump around.

All these factors were however in place and Oersted discovered a fundamental connection between electricity and magnetism. Electric currents cause magnetic fields. The electric current in a long straight wire will produce circular magnetic field lines around the wire. When the wire has a different configuration, the electric currents will cause a magnetic field in a different configuration. Oersted made the important discovery that electric currents cause magnetic fields. Electromagnets work because electric currents cause magnetic fields. Permanent magnets have electric currents at the microscopic level that cause their magnetic fields.

Many other physicists then followed up on Oersted’s pioneering discovery.

Andre Ampere as well as the team of Jean Biot and Felix Savart did experiments to quantify the magnetic field produced by an electric current. Michael Faraday did experiments on electromagnetic induction. Finally James Clerk Maxwell synthesized all this work into the famous Maxwell’s equations.

Oersted’s discovery set the stage for our modern understanding of electrodynamics. Ultimately all magnetic fields are caused by changing electric fields, and changing magnetic fields as well as electric charges cause electric fields.

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