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Free download in PDF Heat Transfer Multiple Choice Questions with Answers for competitive exams. These short objective type questions with answers are very important for competitive exams like IIT-JEE, AIIMS, NEET etc. as well as Board exams. These short solved questions or quizzes are provided by Gkseries.
61
Total emissivity of polished silver compared to black body is
[A]
Same
[B]
Higher
[C]
More Or Less Same
[D]
Very Much Lower
62
Stefan Boltzmann law is applicable for heat transfer by
[A]
conduction
[B]
convection
[C]
radiation
[D]
conduction and radiation combined
63
The thermal diffusivities for solids are generally
[A]
less than those for gases
[B]
jess than those for liquids
[C]
more than those for liquids and gases
[D]
more or less same as for liquids and gases
Answer: more than those for liquids and gases
64
According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to
[A]
absolute temperature
[B]
T2
[C]
T5
[D]
t
65
The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit
[A]
Temperature
[B]
Thickness
[C]
Area
[D]
Time
66
The ratio of the energy absorbed by the body to total energy falling on it is called
[A]
Absorptive Power
[B]
Emissive Power
[C]
Absorptivity
[D]
Emissivity
67
The amount of radiation mainly depends on
[A]
nature of body
[B]
temperature of body
[C]
type of surface of body
[D]
All Of The Above
68
The emissive power of a body depends upon its
[A]
Temperature
[B]
Wave Length
[C]
Physical Nature
[D]
All Of The Above
69
In regenerator type heat exchanger, heat transfer takes place by
[A]
direct mixing of hot and cold fluids
[B]
a complete separation between hot and cold fluids
[C]
flow of hot and cold fluids alternately over a surface
[D]
generation of heat again and again
Answer: flow of hot and cold fluids alternately over a surface
70
If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of