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प्रश्न
Explain briefly the process of heat transfer by radiation.
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
No medium is required for transfer of heat by the process of ______.
Write true or false for a given statement.
Medium is necessary for the transfer of heat by radiation.
Write true or false for a given statement.
Liquids are heated by conduction and radiation.
Write true or false for a given statement.
Black surfaces are the poor absorbers of heat radiations.
Fill in the blank
A hot metallic piece is placed in tap water contained in a bucket. Heat will flow from _______ to _________
Fill in the blank
Heat transfer in liquids and gases is by ________.
______ of heat does not require a medium.
The handles of cooking utensils are made of ______.
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.
