263) When ? is absorptivity, ? is reflectivity and ? is transmittivity, then for a diathermanous body,

? = 1, ? = 0 and ? = 0

? = 0, ? = 1 and ? = 0

? = 0, ? = 0 and ? = 1

? + ? = 1 and ? = 0

Answer is:

? + ? = 1 and ? = 0

Heat Transfer Refrigeration and Air Conditioning MCQ with Answers

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Related Heat Transfer Refrigeration and Air Conditioning MCQ with Answers

264) When there is an addition of water vapour to the air of enclosed space, a gain in __________ is said to occur.

sensible heat

latent heat

specific heat

none of these

Answer is:

latent heat

265) The relative humidity __________ as air gets drier.

increases

decreases

remains same

none of these

Answer is:

increases

266) The central air conditioning system has __________ overall efficiency as compared to individual systems.

same

lower

higher

none of these

Answer is:

higher

267) The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as

Wien's law

Stefan's law

Kirchhoff's law

Planck's law

Answer is:

Kirchhoff's law

Explanation:

According to Kirchhoff's law, the ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body.

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