SESSION 30
I. ANSWER THE FOLLOWING QUESTIONS:
1.Distinguish between reflection of heat and absorption of heat.
2.Clean snow does not melt easily in sunlight. Why?
3.Why cooling fans at the back of a refrigerator are painted black?
4.Give one example of heat transfer by radiation.
SESSION 31:
II. SOLVE THE NUMERICALS :
1.The temperature of two bodies differ by 10℃ on the Celsius scale. How much will they differ on the i) Fahrenheit scale ii) Kelvin scale ?
2.Convert 10℃ in i) Fahrenheit scale ii) Kelvin scale.
3.The normal temperature of human body is 37℃ . What will be its value on the i) Fahrenheit scale ii) Kelvin scale?
Answers
Answer:
A solar thermal collector collects heat by absorbing sunlight. The term "solar collector" commonly refers to a device for solar hot water heating, but may ..
vary...
Answer:
Explanation:
1.Distinguish between reflection of heat and absorption of heat.
2.Newly formed snow reflects about 90 per cent of the sunlight that falls upon it. This means that the sun is powerless to melt clean snow. ... Snow does not melt on a spring day because of the sun's heat. It melts because of the warm air from the sea.
3.Since black is a good heat-absorbing color, it is also a good heat-radiating color. ... One of the things the external coils do is radiate heat, so they are painted black to help that process.
4.The heating of the Earth by the Sun is an example of transfer of energy by radiation. The heating of a room by an open-hearth fireplace is another example. The flames, coals, and hot bricks radiate heat directly to the objects in the room with little of this heat being absorbed by the intervening air.