Heat Transfer MCQ Questions and answers

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Q. Absorptivity of a body will be equal to its emissivity

(A) at all temperatures
(B) at one particular temperature
(C) when system is under thermal equi-librium
(D) at critical temperature

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Q. A steam pipe is to be insulated by two insulating materials put over each other. For best results

(A) better insulation should be put over pipe and better one over it
(B) inferior insulation should be put over pipe and better one over it
(C) both may be put in any order
(D) whether to put inferior OIL over pipe or the better one would depend on steam temperature

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Q. A perfect black body is one which

(A) is black in colour
(B) reflects all heat
(C) transmits all heat radiations
(D) absorbs heat radiations of all wave lengths falling on it

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Q. A non-dimensional number generally associated with natural convection heat transfer is

(A) Grashoff number
(B) Nusselt number
(C) Weber number
(D) Reynold number

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Q. A grey body is one whose absorptivity

(A) varies with temperature
(B) varies with wavelength of the incident ray
(C) is equal to its emissivity
(D) does not vary with temperature and. wavelength of the incident ray

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Q. 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is

(A) 0.45
(B) 0.55
(C) 0.4
(D) 0.75

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Q. If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of

(A) 3
(B) 6
(C) 81
(D) 27

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Q. Depending on the radiating properties, body will be transparent when

(A) p = 0, x = 0 and a = 1
(B) p=l,x = 0, and a = 0
(C) p = 0, T= l, and a = 0
(D) X = 0, a + p = 1

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Q. According to Prevost theory of heat exchange

(A) it is impossible to transfer heat from low temperature source to t high temperature source
(B) heat transfer by radiation requires no medium
(C) all bodies above absolute zero emit radiation
(D) heat transfer in most of the cases takes place by combination of conduction, convection and radiation

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Q. According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to

(A) absolute temperature
(B) square of temperature
(C) fourth power of absolute temperature
(D) fourth power of temperature

Heat Transfer MCQs with answers Page - 1

Q. Absorptivity of a body will be equal to its emissivity

Q. A steam pipe is to be insulated by two insulating materials put over each other. For best results

Q. A perfect black body is one which

Q. A non-dimensional number generally associated with natural convection heat transfer is

Q. A grey body is one whose absorptivity

Q. 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is

Q. If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of

Q. Depending on the radiating properties, body will be transparent when

Q. According to Prevost theory of heat exchange

Q. According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to

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