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प्रश्न
Explain briefly the process of heat transfer by radiation.
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उत्तर
RADIATION. “The transfer of heat energy from a hot body to cold body directly, without heating the medium between two bodies is called RADIATION.”
The radiant heat or thermal radiation is of the form of ELECTROMAGNETIC WAVES. These waves can travel even in vacuum in all directions in straight line with the speed of light. They do not heat the medium through which they pass. Heat radiations are also called INFRA-RED RADIATIONS because the wavelength of heat radiations is longer than that of visible light. These radiations can cause heating effect only if they are absorbed by some material
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संबंधित प्रश्न
Give two examples each of conductors and insulators of heat.
Fill in the blank
Heat transfer in solids is by ______
Select the correct alternative
If we add a lump of ice to a tumbler containing water,
Select the correct alternative
Heat in a liquid is transferred by
Maximum heat is absorbed by a ______ coloured object.
Conduction of heat takes place through a ______ substance.
The earth receives heat from the sun by ______.
How does a fever get lowered by putting a cold compress on the forehead of a patient?
When ice changes into a liquid, it absorbs energy.
Take two similar transparent glass bottles having wide mouths. Put a few crystals of potassium permanganate or pour a few drops of ink in one bottle. Fill this bottle with hot water. Fill the other bottle with cold water. Cover the cold water bottle with a thick piece of paper such as a postcard. Press the postcard firmly with one hand and hold the bottle with the other hand. Invert the bottle and place it on top of the hot water bottle. Hold both the bottles firmly. Ask some other person to pull the postcard. Observe what happens. Explain.
