Edward Appleton

British Physicist, studied the transmission of radio waves

Background

Appleton was clearly a gifted child as he passed the entrance exam to University of London with first class honours at the age of 16. He then went on to St John’s College, Cambridge graduating with honours in 1913. After this, he went to work under William Henry Bragg on crystallography but this was cut short by the start of World War I, when he joined the Royal Engineers.

Radio

After the war, Appleton was appointed Wheatstone Professor of Physics in King’s College at the University of London. It had been proposed by Oliver Heaviside and Arthur Kennelly in 1902 that some waves were reflected back to earth by an electrified layer (E Layer) in the upper atmosphere, this layer was later called an ionosphere. In 1924, Appleton with the help of the British Broadcasting Corporation (BBC) used a station in Bournemouth in the South of England to transmit short waves into the atmosphere to see if they were bounced back off this E Layer.

Radio Location

The signal did bounce back from this layer, they managed by changing the frequency of the waves to determine the height of this layer. It was found that this layer was 60 miles up in the atmosphere. This is the first example of detecting an object by changing the frequency of radio waves bounce off that object, this forms the basis of radar. Robert Watson-Watt (inventor of radar) has stated that, but for Appleton’s scientific work, radar would have come too late to have been of decisive use in the Battle of Britain.

F-Layer

In 1926, Appleton detected a new layer which was higher than the Heaviside-Kennelly E Layer at about 150 miles high. This layer called the F Layer or Appleton Layer can bounce short waves further and it makes global radio communication possible.

The War Years

Appleton became Jacksonian Chair of Natural Philosophy at Cambridge in 1936 and continued his work on atmosphere research. This was cut short by the Second World War were Appleton was appointed Secretary of the Department of Scientific and Industrial Research and Scientific Advisory Committee of the War Cabinet which, in 1941, advised the Government that the manufacture of an atomic bomb was feasible.

Sunspots

During the war, he went to the United States to collaborate efforts between scientists of both nations. While there he studied the effects of sunspots on the ionosphere, he showed that the ionosphere reflecting power varied with sunspot activities. Appleton while working with Dr. J. S. Hey, discovered that sunspots are powerful emitters of short radio waves.

The Awards

Appleton was elected to the Royal Society in 1927, was Knighted in 1941 and won the Nobel Prize in 1947. He was also awarded the highest civilian decoration of the United States – the Medal of Merit and in 1948, he was appointed by the Pope to the Pontificial Academy of Science.

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