Mirrors have been used for ages. It is said that Archimedes used huge mirrors to focus the heat of the sun’s rays on enemy ships to burn them. The same principle is used in solar cookers, where mirrors are used to reflect and focus the sun’s rays on to cooking containers. Astronomers use huge concave mirrors to focus starlight. The mirrors used in telescopes are polished by giving a thin coat of silver or aluminium to the glass. With the telescopes, astronomers can see the heavenly bodies, but even without the telescopes, one can see the moon. A full moon shining overhead is a beautiful sight. But it is also a puzzle, because if the sun and the moon both give the same light, then why is the moonlight more pleasant?The reason is that the moon reflects very little sunlight, in fact, only seven percent of the light it receives The earth reflects about half of the radiation that it receives from the sun Imagine how bright the earth must be looking from the moon! One can even read a book on the moon in the earthlight. However, you do not have to travel to the moon to realize how strong the earth’s light is. Observe the crescent moon soon after all the new moon. The bright crescent is illuminated by the sun. The rest of the moon is illuminated by earthlight. In other words, the light reflected by the earth is falling on the moon. This is being reflected and is strong enough to show the moon faintly. 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 dramatically increases UV-B exposure near the Earth’s surface, as it reflects most of the radiation into the atmosphere, where it is then scattered back toward the surface by aerosols and molecules. Fresh snow can reflect as much as 9.4 percent of the incoming UV radiation. The bright light reflected by it can dazzle and harm your eyes Mountaineers, therefore, use dark glasses.1. Fill in the blanks :Mountaineer’s wear ______ while climbing mountains.a. light glassesb. dark lensesc. dark glassesd. light lenses2. Fill in the blanks :The bright light reflected by fresh snow can _______.a. harm our faceb. harm our eyesc. harm our skind. harm our nose3. Why did Archimedes use mirrors to focus the heat of the sun rays?a. Archimedes used mirrors to focus the heat of the sun’s rays on enemy ships to burn them.b. Archimedes used mirrors to focus the heat of the sun’s rays on enemy ships to shoot them.c. Archimedes used mirrors to focus the heat of the sun’s rays on enemy ships to turn them around.d. Archimedes used mirrors to focus the heat of the sun’s rays on enemy ships to vanish them.4. Choose the correct option :The earth reflects ___ of the radiation received from the sun.a. more than Halfb. fullc. about halfd. one - Third5. The principle of focusing sun rays is used in :a. The principle of focusing sun rays is used in Solar panel.b. The principle of focusing sun rays is used in Solar cooker.c. The principle of focusing sun rays is used in Solar lights.d. The principle of focusing sun rays is used in Solar cells.6. The dim part of the crescent moon is lit by :a. The dim part of the crescent moon is lit by Earth light.b. The dim part of the crescent moon is lit by Moonlight.c. The dim part of the crescent moon is lit by Star light. d. The dim part of the crescent moon is lit by Sunlight.7.  With the _____, astronomers can see the heavenly bodies.a. periscopeb. telegramc. telescoped. satellite8. Mirrors used in telescopes are polished by which coating?a. Mirrors used in telescopes are polished by Silver or potassium coating.b. Mirrors used in telescopes are polished by brass or Aluminium coating.c. Mirrors used in telescopes are polished by gold or Aluminium coating.d. Mirrors used in telescopes are polished by Silver or Aluminium coating.9. State true or false :It is said that Archimedes used small mirrors to focus the heat of the sun’s rays on enemy ships to burn them.a. Trueb. False10. Fill in the blanks :_____ use huge concave mirrors to focus starlight.a. Artistsb. Astronomersc. Astronautsd. Teachers