My Notes
The fastest mode of heat transfer is
1. Conduction
2. Radiation
3. Convection
4. all are equally fast
In which of the following process, convection does not take place primarily ?
(1) Sea and land breeze
(2) Boiling of water
(3) Warming of glass of bulb due to filament
(4) Heating air around a furnace
On a clear sunny day, an object at temperature \(T\) is placed on the top of a high mountain. An identical object at the same temperature is placed at the foot of the mountain. If both the objects are exposed to sun-rays for two hours in an identical manner, the object placed on the top of a mountain will register a temperature:
| 1. | higher than the object at the foot. |
| 2. | lower than the object at the foot. |
| 3. | equal to the object at the foot. |
| 4. | none of the above. |
Taking into account the radiation that a human body emits which of the following statements is true?
| 1. | The radiation is emitted only during the day. |
| 2. | The radiation is emitted during the summers and absorbed during the winters. |
| 3. | The radiation emitted lies in the ultraviolet region and hence is not visible. |
| 4. | The radiation emitted is in the infra-red region. |
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