Physics - Study Mode

[#831] The cover of a solar cooker is made of glass because
Correct Answer

(C) It retains the heat inside by the green house effect

Explanation

Solution: Cover of the solar cooker is made of glass because glass allows the sunlight to pass through it and concentrate at one focal point, it also prevents heat to escape out of the cooker.

[#832] The base of an electric iron is brightly polished mainly
Correct Answer

(C) To reduce heat loss by radiation

Explanation

Solution: Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.

[#833] A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because
Correct Answer

(B) The stone conveys the heat away from the feet more rapidly than the carpet

Explanation

Solution: Both the floor and the carpet have the same temperature as both are exposed to the same atmosphere. So the feet losing more heat, the floor appears cooler to the feet.

[#834] Global warming is expected to result in
Correct Answer

(D) All of the above

Explanation

Solution: Global warming is expected to result in increase in level of sea, change in crop pattern and change in coast line.

[#835] Why two thin shirts can keep us warmer than a single thick shirt in winter ?
Correct Answer

(C) Air layer between two shirts behaves like insulating media

Explanation

Solution: Two thin shirts can keep us warmer than a single thick shirt in winter because of the air that is trapped between the two thin shirts. This air acts as an insulator and ensures that heat does not escape.