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Telegraph was made in 1830s by Samuel Morse. A student of Chandranagar Banga Vidyalaya from West Bengal explained the working of telegraph at Jawaharlal Nehru National Science Mathematics and Environment Exhibition for Children. To know how telegraphs works, watch this video.
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License:[Source CIET, NCERT ]Feb. 20, 2017, 11:48 a.m.

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