Sahil Gupta

Sahil is the CEO at Sawan Books. He pursued his Bachelor’s Degree in Bussiness from the University of Chicago, USA and currently working on his ultimate goal - ‘To see a book in every child’s hand.’ .

Radio

Radio owes its development to two other inventions— the telegraph, and the telephone. In fact, all three technologies are closely related. Few radio broadcasts travel through the air exclusively, while many are sent over telephone wires. In the 1860s, James Clerk Maxwell, a Scottish physicist, predicted the existence of radio waves, and in 1886 Heinrich

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Radar

Heinrich Hertz in Germany calculated that an electric current swinging very rapidly back and forth in a conducting wire would radiate electromagnetic waves into the surrounding space. Today we would call such a wire an ‘antenna’. He created such a wire in 1886, and detected such oscillations in his lab, using an electric spark, in

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Photostat

In 1937, an American law student Chester Carlson invented a copying process based on electrostatic energy called Xerography. Xerography became commercially available in 1950 by the Xerox Corporation. The word ‘Xerography’ comes from the Greek for ‘dry writing.’ Carlson had been frustrated with the slow mimeograph machine, and the cost of photography, and that lead

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