The vast array of electrical devices we take for granted today can be traced back to the discoveries of British scientist Michael Faraday who, during his long career, made the first motor, generator and transformer.
Thevast array of electrical devices we take for granted today can be traced back to the discoveries of British scientist Michael Faraday who, during his long career, made the first motor, generator and transformer.
Faraday’s electric motor of 1821 depended on a discovery a year earlier by Danish scientist Hans Christian Ørsted.
While preparing for a lecture about electricity, Ørsted noticed how an electric current in a wire made a nearby magnetic compass needle twitch.
British scientist Humphry Davy, Faraday’s mentor, realised an electromagnetic force should be able to produce sustained motion, not just a twitch.
But he couldn’t make a device to achieve it.
Faraday did – by suspending a wire in a pool of mercury with a magnet in it. Current made the wire whirl around the magnet.
When Faraday wrote about his motor, he forgot to mention Davy’s involvement.
Davy was furious and as a result Faraday temporarily stopped work on electromagnetism.
Other scientists carried on the research.
In 1825, English physicist William Sturgeon realised he could strengthen the electromagnetic force by wrapping the current-carrying wire into a coil around an iron bar. He had made the first electromagnet.
Humphry Davy died in 1829, and Faraday (1791–1867) resumed his work on electromagnetism.
He discovered that moving a magnet to and fro made current flow in a wire nearby.
He found the same thing happened if the wire moved instead of the magnet.
This is called electromagnetic induction – the magnet ‘induces’ electric forces in the wire.
This forms the basis of electric generators, and Faraday made a simple generator in 1831.
The same year he made what was effectively the first transformer.
The modern world depends heavily on these to increase or decrease the voltage of a supply.
Electricity is normally produced in power stations at 30,000 volts, but is ‘transformed’ to much higher voltages for efficient transmission along power lines.
Then it is transformed down again in a series of steps before reaching our homes at 230 volts.
Many devices inside our homes, such as mobile phone chargers, contain small transformers that change the voltage of mains electricity, typically down to 6, 9 or 12 volts.
Faraday also introduced the idea of electric and magnetic ‘fields’.
He was the first to draw their shapes and show how they interact.
Faraday was a great experimental scientist and innovator who also made important discoveries in chemistry and became well-known for popularising science through his public lectures at the Royal Institution in London.
One of his friends, the brilliant Scottish physicist James Clerk Maxwell, developed Faraday’s ideas about electric and magnetic fields into a mathematical theory.
In the 1860s, he derived four equations to describe their behaviour.
By combining those four equations into one, Maxwell discovered that electromagnetic fields oscillate, and radiate through space in waves.
According to his equation, the wave’s speed is identical to the speed of light. He had proved light is an electromagnetic wave.
Radio waves, microwaves, infrared, ultraviolet, X-rays and gamma rays are also electromagnetic radiation, although not all were known in Maxwell’s day.