1) Heat transfer deals with the rate of
a. work transfer
b. temperature transfer
c. energy transfer
d. none of the above
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2) Which among the following has lowest thermal conductivity among the others?
a. silver
b. water
c. mercury
d. copper
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3) In gases, the transfer of heat takes place by
a. volumetric density
b. transporting energy with free electrons
c. unstable elastic collision
d. random molecular collision
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4) How does the heat transfer take place in metals?
a. volumetric density
b. transporting energy with free electrons
c. unstable elastic collision d. random molecular collision
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5) Internal energy of a substance is associated with
a. microscopic modes of energy
b. macroscopic modes of energy
c. both a. and b.
d. none of the above
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6) In which phase of a substance does conduction mode of heat transfer take place?
a. solid
b. liquid
c. gaseous
d. all of the above
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7) Mass transfer does not take place in
a. conduction heat transfer
b. convection heat transfer
c. radiation heat transfer
d. none of the above
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8) What is the condition for conduction mode of heat transfer between two bodies?
a. the two bodies must be in physical contact
b. there must be temperature gradient between the bodies
c. both a. and b.
d. none of the above
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9) In which mode, does the heat energy transfer between two bodies when they are separated by some distance and there is no any medium between them?
a. conduction mode of heat transfer
b. convection mode of heat transfer
c. radiation mode of heat transfer
d. heat transfer cannot takes place with above condition
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10) The radiant heat emitted by any body travels at the speed
a. less than the speed of light
b. more than the speed of light
c. equals to the speed of light
d. unpredictable
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11) In convection heat transfer energy transfer takes place between
a. two solid surfaces connected physically
b. solid surface and fluid system in motion
c. both a. and b.
d. none of the above
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12) What is the correct formula for the rate of heat transfer (q) from a surface of body of the area A to the surrounding fluid, when surface of the body is
at temperature Ts and the surrounding fluid is at temperature T∞?
Where,
k = conductivity of the body
h = coefficient of convection
a. q = k A (Ts – T∞)
b. q = h A (Ts – T∞)
c. q = (h/k) A (Ts – T∞)
d. q = (1/h) A (Ts – T∞)
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13) The convection heat transfer coefficient depends upon
a. the thermal properties of fluid
b. geometry of the system
c. characteristics of the fluid flow
d. all of the above
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14) In a process of heat transfer by convection from a body to the surrounding fluid, the convection heat transfer coefficient
a. remains constant over the entire surface of the body
b. does not remain constant over the entire surface of the body
c. none of the above
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Answer
Explanation
Related Ques
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ANSWER: does not remain constant over the entire surface of the body
Explanation:
No explanation is available for this question!
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15) Which two processes are unitedly responsible in the transfer of heat between solid surface and surrounding fluid?
a. conduction and convection
b. conduction and mass transfer
c. convection and mass transfer
d. none of the above
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16) When the surface of a body is at higher temperature than the surrounding fluid, then the heat flows firstly from surface of the body to the adjacent layer of fluid by
a. convection
b. conduction
c. radiation
d. none of the above
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17) The fluid flow in which the fluid particles in one layer do not mix with the fluid particles in the other layer is called as
a. laminar flow
b. turbulent flow
c. layer flow
d. none of the above
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18) Generally, all the fluid particles in flowing fluid
a. flow at a constant velocity
b. flow at various velocities
c. flow at a velocity as high as possible
d. none of the above
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19) What is the relation between the rate of convection heat transfer and the rate of mixing in turbulent fluid flow?
a. the rate of convection heat transfer decreases with increase in the rate of mixing in turbulent fluid flow
b. the rate of convection heat transfer increases with increase in the rate of mixing in turbulent fluid flow
c. the rate of convection heat transfer does not affected by the change in the rate of mixing in turbulent fluid flow
d. none of the above
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Answer
Explanation
Related Ques
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ANSWER: the rate of convection heat transfer increases with increase in the rate of mixing in turbulent fluid flow
Explanation:
No explanation is available for this question!
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20) Viscosity of a fluid can be defined as
a. change in density of the fluid per unit temperature
b. flow resistance offered by the fluid
c. flow velocity change
d. none of the above
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21) The radiation takes place
a. through molecular communication
b. through vacuum
c. both a. and b.
d. none of the above
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22) Which phenomenon is related to the term radiation?
a. magnetic phenomenon
b. gravity
c. electromagnetic phenomenon
d. none of the above
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23) Thermal radiation takes place from a body by electromagnetic waves as a result of
a. the weight of the body
b. the magnetic power of the body
c. the temperature of the body
d. none of the above
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24) The range of waves within which all possible frequencies of electromagnetic radiation are represented is called as
a. electromagnetic frequencies
b. electromagnetic spectrum
c. electromagnetic range
d. none of the above
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25) How is the wavelength of radiation (λ) calculated, when propagation velocity (C) and frequency (ν) of the radiation is given?
a. λ = C x ν
b. λ = C / ν
c. λ = ν / C
d. none of the above
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26) What is the approximate wavelength range of thermal radiation?
a. 0.1 to 100 μm (micrometer)
b. 0.1 to 100 nm (nanometer)
c. 0.1 to 100 cm (centimeter)
d. none of the above
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27) The wavelength range of the visible light is about
a. 350 to 750 μm (micrometer)
b. 350 to 750 nm (nanometer)
c. 350 to 750 cm (centimeter)
d. none of the above
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28) Which of the following bodies will not be able to emit radiation continuously?
a. a body with very high temperature placed in air medium
b. a body with temperature 0 oC placed in air medium
c. a body with temperature 0 oC placed in vacuum
d. none of the above
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29) When a body receives radiation in the wavelength range of 0.1 to 100 μm (micrometer), then its temperature
a. increases
b. decreases
c. does not change
d. unpredictable
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30) What is emissive power of a body?
a. total radiation emitted by the body per unit volume and time
b. total radiation emitted by the body per unit temperature and time
c. total radiation emitted by the body per unit area and time
d. none of the above
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Answer
Explanation
Related Ques
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ANSWER: total radiation emitted by the body per unit area and time
Explanation:
No explanation is available for this question!
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31) Which of the following is NOT a type of condensation heat transfer process?
a. drop-wise condensation
b. bulk-wise condensation
c. film-wise condensation
d. none of the above
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32) Which surface does the drop-wise condensation occur on?
a. wettable surface
b. non-wettable surface
c. both a. and b.
d. none of the above
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33) How can the rates of heat transfer from drop-wise condensation and film condensation be compared?
a. the rate of heat transfer from drop-wise condensation is lower than that of film condensation
b. the rate of heat transfer from drop-wise condensation is higher than that of film condensation
c. the rate of heat transfer from drop-wise condensation is equal to that of film condensation
d. unpredictable
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Answer
Explanation
Related Ques
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ANSWER: the rate of heat transfer from drop-wise condensation is higher than that of film condensation
Explanation:
No explanation is available for this question!
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34) Film condensation occurs on a surface when
a. condensate can wet all the surface
b. condensate cannot wet the surface
c. both a. and b.
d. none of the above
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35) The thermal resistance for heat transfer is low in
a. drop-wise condensation
b. film condensation
c. both drop-wise and film condensation
d. unpredictable
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