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?