Question

Read the passage given below and complete the sentences that follow :(1x8=8 marks)Mirrors have been used since ages. It is said that Archimedes used huge mirrors to focus the heat of the sun's raysom enemy ships to burn them. The same principle is used in solar cookers where mirrors are used to reflect and focusDe sun's rays on to cooking containers. Astronomers use huge concave mirrors to focus starlight. The mirrors useda telescopes are polished by giving a thin coat of silver or aluminium to the glass. With the telescopes astronomerscan see the heavenly bodies but even without the telescopes one can see the moon. A full moon shining overheada beautiful sight. But it is also a puzzle because if the sun and the moon both give the same light then why is themoonlight more pleasant ?The reason is that the moon reflects very little sunlight in fact only seven percent of the light it receives. Theearth reflects about half of the radiation that it receives from the sun. Imagine how bright the earth must be lookingSom the moon ! One can even read a book on the moon in the earthlight. However you do not have to travel all thesay to the moon to realize how strong the earth light is. Observe the crescent moon soon after all the new moon. TheEright crescent is illuminated by the sun. The rest of the moon is illuminated by earthlight. In other words the lightafected by the earth is falling on the moon. This is being reflected back to us and is strong enough to show the moonfaintly. As the crescent increases in size this effect disappears.Fresh snow is the best reflector of sunlight in nature. As a highly reflective substance snow dramaticallyTeases UV-B exposure near the Earth's surface as it reflects most of the radiation back into the atmosphere whereA is then scattered back toward the surface by aerosols and molecules. Fresh snow can reflect as much as 9.4 percent oftie incoming UV radiation. The bright light reflected by it can dazzle and harm your eyes. Mountaineers therefore usedark glassesA) Answer the following questions:(1 x 4 = 4)Mirrors used in telescopes are polished by which (iii) The bright light reflected by fresh snow cancoating?Mountaineers wearwhile climbing (iv) Why did Archimedes used mirrors to focus themountains.heat of the sun rays?(8) Choose the correct alternatives:(1 x 4 = 4)0 The earth reflectsof the radiation (iii) The dim part of the crescent moon is lit by :received from the sun.(a) sunlight(a) about one-fourth(b) satellite(b) about three-fourth(c) stars light(c) about two-third(d) earth light(d) about half(iv) With theastronomers can see theThe principle of focusing the sun rays is used in : heavenly bodies.(a) Solar cooker(a) telegraph(b) Pressure cooker(b) telephone(c) Inverter(c) telescope(d) None of the above(d) television`​

Answer 1

Answer:

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Answer 2

Answer:

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