5th April 2011 Linking up Nature with Electricity

Electricity

1784 Charles-Augustin de Coulomb quantified the force between electrical charges, discovering the inverse square law that is now known as Coulomb’s law.

Electricity and Nature

1750s Benjamin Franklin postulated and demonstrated that lightning is a form of electricity with his invention of the lightning rod and a particularly infamous kite flight.

1791 Luigi Galvani discovered that the muscles of dead frogs could be excited by electrical sparks.

Electricity and Chemistry

1800 Italian physicist Alessandro Volta developed the first chemical battery, known as the voltaic pile.

Electricity and Magnetism

1820 Danish physicist Hans Christian Oersted observed the twitch of a compass needle in the presence of an electric current which was an experiment he performed for the first time in a lecture!

Benjamin Franklin had magnetised needles by discharging electricity through them
Sailors reported the reversal of polarity of compass needles after their ships were struck by lightning.

1831 Michael Faraday showed that a changing magnetic field could produce an electric field.

James Clerk Maxwell completed the fundamental theory of electromagnetism, and the realised that light is an electromagnetic wave.

Electromagnetism

If a compass is put to the east or west of a north pointing wire (with current flowing south to north), it will point to the NW. When above, it will also point NW, but when below, it points NE. Why is this? It's is because the magnetic field spirals around the wire according to the right hand rule. The angle of this deviation is affected by the size of the current. The angle would be larger if it were not for the effect of the earth's magnetic field. This works in the same way as the field around the wire, if you imagine a wire stretching from the South Pole to North.

[Source: The Birth of Electromagnetism-1820]