Explain why (a) A diamond glitters in a brightly lit room, but not in a dark romm. (b) A crack in window pane appears silvery. (c ) The bubbles of air rising up in a water tank appear silvery when viewed from top.
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(a) A daimond glitters in a brightly lit room because light entering the diamond from any face suffers multiple reflections and does not come out. The diamond appears illuminated from inside. This would not happen in a dark room. (b) A crack in a window pane appears silvery on account of total internal reflection on light in the crack. (c ) The bubbles of air rising up in a water tank appear silvery when viewed from top again on account of total internal reflection of light from the bubble.
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Explain why (a) A diamond glitters in a brightly lit room, but not in a dark room. (b) A crack in a window pane appears silvery. ( c) The bubbles of air rising up in a water tank appear silvery when viewed from top.
Why does water tank appear shalleower when veiwed from the top ?
Paheli kept some water in a beaker for heating. She observed that tiny bubbles appeared before the water started to boil. She boiled the water for about 5 minutes and filled it in a bottle up to the brim and kept the bottle air tight till it cooled down to room temperature (a) Why did the tiny bubbles appeared ? (b) Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer.
Assertion : An empty test tube dipped into water in a beaker appears silver, when viewed from a suitable direction. Reason : Due to refraction of light, the substance in water appears silvery.
Arrange the following steps in a sequential order to explain the formation of conventional currents through ventilation. (a) the cold air enters into the room through windows from high pressure to low pressure region (b) hot air in the room is less denser and it raises up (c ) the rooms are provided with ventilators at the top (d) hot air passes out through the ventilators it creates low pressure region in the room
Shows a large closed cylindrical tank containing water, Initially the air trapped above the water surface has a height h_(0) and pressure 2p_(0) where p_(0_ is the atmospheric pressure. There is a hole in the wall of tank at a depth h_(1) below the top from which water comes out. A long vertical tube is connected as shown. (a) Find the height h_(2) of the water in the long tube above the top initially. (b) Find the speed with which water comes out of hole.(c)Find the height of the water in the long tube above the top when the water stops coming out of the hole.
(a) Give reasonwhy copper is used to make hot water tanksbut steel (an alloy of iron) is not. (b). Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.
