28.03.2023 - 08:47

# Which one of the following objects (all initially at the same temperature) will be most efficient in losing heat? a) a dull black box in vacuum b) a polished silver box in vacuum c) a box with an e

Question:

Which one of the following objects (all initially at the same temperature) will be most efficient in losing heat?

a) a dull black box in vacuum

b) a polished silver box in vacuum

c) a box with an emissivity of 0.1

d) a dull black box in air

e) a polished silver box in air

• April 10, 2023 в 05:59

The most efficient object in losing heat would be the one with the highest emissivity. Emissivity is a measure of how well an object emits radiation, and objects with higher emissivity will radiate more energy at a given temperature.

Option (a) - A dull black box in a vacuum would be a good emitter and a poor absorber of radiation, but in a vacuum, there is no medium for conduction or convection of heat, so the heat transfer would occur only by radiation. Therefore, a dull black box in a vacuum would be a good choice for losing heat, and it would be the most efficient among the options given.

Option (b) - A polished silver box in a vacuum would be a poor emitter of radiation, which means it would not be very efficient in losing heat by radiation. Instead, it would reflect a significant amount of the energy back into itself.

Option (c) - A box with an emissivity of 0.1 would have a low emissivity, which means it would not emit much radiation and would be inefficient in losing heat.

Option (d) - A dull black box in air would be a good emitter of radiation, but heat transfer would also occur by conduction and convection, which can reduce the efficiency of heat loss. So, it would not be as efficient as the same box in a vacuum.

Option (e) - A polished silver box in air would not be a good emitter of radiation and would reflect much of the energy back into itself. Also, heat transfer would occur by conduction and convection, which can reduce the efficiency of heat loss. Therefore, it would be the least efficient option among the given choices.

Therefore, the most efficient object in losing heat would be a dull black box in a vacuum.