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Know the scientist: Sir Lawrence Bragg

Sir Lawrence Bragg (1890 - 1971) was an Australian-born British physicist, who came up with the Bragg’s Law of x-ray diffraction to determine crystal structure. In 1915, at the age of 25 years, he won the Nobel Prize for Physics along with this father Sir William Bragg for this scientific contribution. He is the youngest to have won a Nobel in Physics.

Lawrence Bragg was born in Adelaide, South Australia, to Sir William Henry Bragg, professor of mathematics and physics at the University of Adelaide, and Gwendoline, daughter of Sir Charles Todd, government astronomer of South Australia. Even as a child, he showed interest in science and mathematics. Lawrence Bragg received his early education at St. Peter’s College and then a degree in mathematics in Adelaide University in 1908. In 1912, he came to England (along with his father) to study Natural Science Tripos in Trinity College, Cambridge, as an Allen Scholar.

The same year, he was introduced to the work of the German physicist Max von Laue by his father. Laue had asserted that x-rays could be diffracted by passing them through crystals. William and Lawrence Bragg carried out a series of experiments at Cambridge to test Laue’s assertion. Lawrence Bragg published the Bragg equation, which tells at what angles x-rays will be most efficiently diffracted by a crystal when the X-ray wavelength and the distance between the crystal atoms are known. This provided a powerful tool for studying crystals' structures.

Lawrence Bragg also showed how the two kinds of atoms, sodium and chlorine, are arranged in rock salt. Meanwhile, his father designed the x-ray spectrometer, a device to make exact measurements of x-ray wavelengths. Using the instrument, the duo determined many atomic arrangements, including that of diamond.

From 1915 to 1919, Bragg served as a technical adviser, determining the distance of enemies’ artillery from the sound of their guns, in the British army during World War I.

Lawrence Bragg won many awards and honours. He was knighted in 1941. He was awarded the Hughes Medal of the Royal Society in 1931; the Royal Medal of the same Society in 1946, and the Roebling Medal of the Mineral Society of America in 1948. Together with his father, he published various scientific papers on crystal structure.

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Printable version | Nov 30, 2020 7:22:34 AM | https://www.thehindu.com/children/know-the-scientist-sir-lawrence-bragg/article33130707.ece

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