The work of Michael Faraday
The phenomenon known as electro-magnetism was discoved by Hans Christian Oersted, the Danish savant, who published his work on this in 1820.
Oersted showed that a magnetic compass needle could be moved by a wire carrying an electric current.
Faraday repeated many of Oersted's experiments and he made a breakthrough that took things one step further.
's sketch of the experiment that revealed the phenomenon he called electro-magnetic rotations. The drawing is from Faraday's own notebook and is courtesy of the Royal Institution.
Faraday's work electro-magnetic rotations
On 4th September 1821, Michael Faraday
discovered that a vertically mounted wire carrying an electric current would rotate continuously round a magnet sticking out of a bowl of mercury. He named this phenomenon electro-magnetic rotations.
Faraday was investigating electro-magnetism
, which describes the relationship between electricity
. Hans Christian Oersted had shown that a magnetic compass needle could be caused to move by a wire carrying an electric current. Faraday showed that it was possible to produce continuous motion from the interaction of electricity and magnetism.
Here is a diagram showing the set-up of his experiment.
Illustration : Paul Weston
On the right is a bowl of mercury with a magnet mounted vertically in the centre of it. One end of the magnet sticks up, in this case the north pole. Mounted vertically above the bowl is a piece of wire, long enough to reach into the mercury and suspended from a simple frame. The wire is free to swing in any direction.
The suspended wire is connected to a copper wire leading from one terminal of a battery
, which will provide the current. Another copper wire connects the other battery terminal to the mercury in the bowl.
When the battery is connected up, the suspended wire rotates continuously round the magnet. It will keep going until the battery runs out or is disconnected. If the magnet's north pole is uppermost, it rotates in an anti-clockwise direction. If the south pole is uppermost, it rotates clockwise.
Why is this significant?
This experiment was Faraday's first independent contribution to electro-magnetism
, a field of chemistry in which he would make many important discoveries. It is the first time that continuous motion had been produced from chemical energy it showed that it was possible to produce such motion from the interaction of electricity and magnetism. This phenomenon is the principle behind the electric motor
What did Faraday do next?
Ten years went by before Faraday could return to the sustained study
of electro-magnetism but when he did so, he made another big breakthrough. He discovered electro-magnetic induction and invented the first
electrical transformer >