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प्रश्न
Why does the bottom of a lake not freeze in severe winter though the surface is all frozen?
उत्तर
Lakes don’t completely freeze because the ice (and eventually snow) on the surface acts to insulate die water below. To freeze water into ice, a large quantity of heat is to be withdrawn. This heat cannot be
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संबंधित प्रश्न
Fill in the blank
Heat is a form of _______.
Define the term calorie. How is it related to joule (the S.I. unit of heat)?
What will absorb heat?
Iron griddle (tava)
What will absorb heat?
Wooden board
What will absorb heat?
Glass
1 calorie is 4.81 joules.
We feel the heat on our body when the ______ shines.
A circular metal loop is heated at point O as shown in Figure 4.6.
(i) In which direction would heat flow in the loop?
(ii) In which order are the pins at points P, Q and R fixed with the help of wax fall if points O, P, Q and R are equidistant from each other?
In arrangements, A and B shown in Figure 4.7, pins P and Q are fixed to a metal loop and an iron rod with the help of wax. In which case are both the pins likely to fall at different times? Explain.
Black color is a ______ absorber of heat.
