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Rohan was studying in a science college ...

Rohan was studying in a science college and was staying with his grand father. One day, the old torch which was being used by Rohan's grand father stopped wirking. He asked Rohan to purchase a new torch for him. Rohan himself made a torch using LED with a small recharge battery and gave it to his grand father as a gift. Rohan explained the advantages of LED over a bulb. Rohan's grand father was very happly.
Read the above passage and answer the following question:
(i) What is LED ? Name the two materials used in making LED, whose light falls in the visible region.
(ii) Why LED is a better choice than a bulb in torch?
(iii) What do you think about the attitude of Rohan towards his grand father?

Text Solution

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(i) LED stands for light emitting diode. The following materials are used in making LEDs whose light falls in the visible region, Gallium-phosphide (GaP)-giving red or green light Gallium-arsenide-phosphide (GaAsP)-giving red or yellow light.
(ii) LED is better than concentrational bilb as the torch with LED is handy and light. It gives intense light and consumes less power.
(iii) Rohan had a great love and respect for his grand father. He proved it by making a tirch for him using new technology. By this act, Rohan earned more love and affection from his grand father.
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Rohan's mother was "feed up" of his laziness.