By Team Aakash Byju's | 20th January 2023
A body with large reflectivity is a poor emitter.
The absorption power of a body with large reflectivity is poor. This turns the body into a poor emitter.
A brass tumbler feels much colder than a wooden tray on a chilly day.
Brass is a good conductor of heat. So, it readily absorbs the temperature of the body, making us feel cool.
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A brass tumbler feels much colder than a wooden tray on a chilly day.
Whereas wood is a poor conductor of heat, and thus when touched, it absorbs a little amount of heat from our body. So, the drop in temperature in our body is negligible making us feel warmer.
An optical pyrometer (for measuring high temperatures) calibrated for ideal black body radiation gives too low a value for the temperature of a red-hot iron piece in the open but gives a correct value for the temperature when the same piece is in the furnace.
The black body radiation equation is: E = σ(T − T ), where E = Radiation energy T = Temperature of optical pyrometer T = Temperature of open space σ = Constant T = 0 in the furnace => E (in furnace) > E(open space)
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The earth without its atmosphere would be inhospitably cold.
Without the atmospheric gases, heat cannot be trapped, and all the heat would be radiated back from the earth's surface. This makes the earth inhospitably cold.
Heating systems based on the circulation of steam are more efficient in warming a building than those based on the circulation of hot water.
At 100° C, the amount of heat possessed by steam is more than that of the heat possessed by 1 gram of water. Thus, the circulation of steam is more efficient than the circulation of water in warming a building.