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Q1:, Fill in the blanks with the proper words., , a. The wavelength of visible light is between, re and ........, , b. GMRT is used for ....... waves., , c. A certain X-ray telescope is named after, SGSNTSE sass avn ;, , d. The first scientist to use a telescope for, space observation Wa ...............606, , e. The biggest optical telescope in India is, situated at......... :, , Solution :, , a. The wavelength of visible light is between, 400 nm and 800 nm., , b. GMRT is used for radio waves., , c. Acertain X-ray telescope is named after, scientist Subramanian chandrashekhar., , d. The first scientist to use a telescope for, space observation was Galileo Galilei., , e. The biggest optical telescope in India is, situated at Aryabhatt Research Institute of, Experimental Sciences, Nanital.

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Q2:, Form pairs, , ‘A Groups ‘B’ Groups, , (i) X-rays (a) GMRT, , (ii) Optical Telescope = (b) ISRO, , (iii) Indian radio (c) Hubble telescope, (iv) Launching (d) Chandra, , artificial satellites, , , , , , , , , , , , Solution :, , ‘A’ Groups [‘B’ Groups, (i) X-rays |(d) Chandra, (ii) Optical telescope eae, (iii) Indian radio (a) GMRT, (iv) Launching artificial |, , , , satellites Co) ISRO

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“<< What are the difficulties in using ground, based optical telescopes? How are they, , Overcome?, Ans. Visible light and radio waves emitted by, , heavenly bodies in the space pass through the, atmosphere before reaching the earth surface., During this journey, some light is absorbed by, atmosphere and intensity of the light reaching the, earth surface decreases. Besides, temperature and, ' air pressure causes the atmospheric turbulence and, thus, light rays changes their path and shakes the, position of the image. City lights during night and, bright sunlight during day also put limitation on, using optical telescopes on the earth. Sometimes, optical telescopes can’t perform as cloud cover, reduces the visibility. This issue is overcome either, of the following ways :, (1) To reduce the intensity of these problems,, optical telescopes are situated on mountain top,, away from inhabited places. However, limitation, , caused due to atmosphere still persist., (2) To get rid of problems in situating telescope on, , the earth, scientists have successfully placed the, , telescope in the space.