Explanation
Actually, the process of radiation does not required any material for transmission of heat.
Thermal radiation travels with the velocity of light and hence the fastest mode of the transfer. Thermal radiations is always transmitted in a straight line.
In conducting rod given heat transmits so burning temperature does not reach soon. In wooden rod heat doesn’t conducts.
The rate of heat loss is proportional to the difference in temperature. The difference of temperature between the tea in cup A and the surrounding is reduced, so it loses less heat. The tea in cup B loses more heat because of large temperature difference. Hence, the tea in cup A will be hotter.
No. in convection the hot liquid at the bottom becomes lighter and hence it rises up. In this way the base of the convection is the difference in weight and upthrust. In the state of weightlessness this difference does not occur, so convection is not possible.
All wavelengths are emitted.
Black bulb absorbs more heat in comparison with painted bulb. So air in black bulb expands more. Hence the level of alcohol in limb X falls while that in limb Y rises.
When salt crystals dissolve, crystal lattice is destroyed. The process requires a certain amount of energy (latent heat) which is taken from the water.
In vessel (B), a part of intermolecular bonds has already been destroyed in crushing the crystal. Hence less energy is required to dissolve the powder and the water will be at higher temperature.
If the sheet is heated then both d1 and d2 will increase since the thermal expansion of isotropic solid is similar to true photographic enlargement.
Due to evaporation cooling is caused which lowers the temperature of bulb wrapped in wet hanky.
Anomalous density of water is given by (a). It has maximm density at 4oC. When ice is formed it floats.
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