1) The conduction heat transfer with combination of transfer of material also is called as
a. material conduction heat transfer
b. convection heat transfer
c. solid convection heat transfer
d. none of the above
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2) According to the Fourier's law of heat conduction, the rate of heat transfer by conduction depends upon
a. area of cross section normal to the heat flow
b. temperature gradient
c. both a. and b.
d. none of the above
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3) What is the temperature gradient in the conduction heat transfer?
a. change in temperature per unit change in time
b. change in temperature per unit change in distance in the direction of heat flow
c. change in temperature per unit change in cross-sectional area normal to the direction of heat flow
d. change in temperature per unit change in cross-sectional area parallel to the direction of heat flow
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Answer
Explanation
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ANSWER: change in temperature per unit change in distance in the direction of heat flow
Explanation:
No explanation is available for this question!
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4) Why is the negative sign introduced in the equation of Fourier's law of heat conduction?
q = – kA (dT / dx)
a. because heat transfer rate is inversely proportional to temperature gradient
b. because value of thermal conductivity k is negative
c. because heat is transferred from higher temperature to lower temperature
d. none of the above
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Answer
Explanation
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ANSWER: because heat is transferred from higher temperature to lower temperature
Explanation:
No explanation is available for this question!
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5) The value of thermal conductivity k depends upon
a. the material through which the heat is transferred
b. the intensity of heat energy which is being transferred
c. the area which is parallel to the heat transfer
d. all of the above
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Answer
Explanation
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ANSWER: the material through which the heat is transferred
Explanation:
No explanation is available for this question!
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6) The materials which have low thermal conductivity are called as ____________
a. thermal conductors
b. thermal resistors
c. thermal insulators
d. none of the above
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7) How does the radiation heat transfer occur through perfect vacuum?
a. by light waves
b. by electromagnetic waves
c. both a. and b.
d. none of the above
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8) The Stefan-Boltzmann law of thermal radiation is applicable for
a. white body
b. gray body
c. black body
d. all of the above
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9) According to the Stefan-Boltzmann law of thermal radiation for a perfect radiator, the rate of radiant energy per unit area is proportional to
a. the temperature of that radiator
b. the square of the temperature of that radiator
c. the cube of the temperature of that radiator
d. the fourth power of the temperature of that radiator
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Answer
Explanation
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ANSWER: the fourth power of the temperature of that radiator
Explanation:
No explanation is available for this question!
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10) In the equation for the rate radiant heat energy from a perfect radiator q = σ A T4 the constant σ is called as
a. Black body constant
b. Radiation constant
c. Stefan-Boltzmann constant
d. none of the above
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11) Which of the following fluid can be considered as an ideal fluid?
a. viscous fluid
b. non-viscous fluid
c. compressible fluid
d. all of the above
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12) Consider a fluid of height H, flowing on a stationary plate as shown in figure. The top most layer of the fluid is moving with velocity U0.
Which of the following condition is correct for the given condition?
a. The shear stress (τ) is directly proportional to (H x U0)
b. The shear stress (τ) is directly proportional to (H / U0)
c. The shear stress (τ) is directly proportional to (U0 / H)
d. none of the above
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Answer
Explanation
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ANSWER: The shear stress (τ) is directly proportional to (U0 / H)
Explanation:
No explanation is available for this question!
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13) What is the correct formula for the shear stress (τ) in a flowing fluid according to the Newton's law of viscosity?
Where,
μ = absolute viscosity of the flowing fluid
(du / dy) = change in velocity of a layer per unit change in distance of that layer from the surface
A = area of the surface on which the fluid is flowing
a. (τ) = (1 / μ) (du / dy)
b. (τ) = μ (du / dy)
c. (τ) = μ A (du / dy)
d. none of the above
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14) What is the SI unit for absolute or dynamic viscosity (μ)?
a. Ns/m2
b. Nm2/s
c. N/m2s
d. N/m2
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15) What is the relation between the absolute viscosities of liquid and gas?
a. (μliquid) ≈ (μgas)
b. (μliquid) << (μgas)
c. (μliquid) >> (μgas)
d. none of the above
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16) The viscosity of a liquid
a. increases with increase in liquid temperature
b. decreases with increase in liquid temperature
c. is not affected by the change in liquid temperature
d. is unpredictable
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Answer
Explanation
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ANSWER: decreases with increase in liquid temperature
Explanation:
No explanation is available for this question!
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17) How is the viscosity of gas affected by change in its temperature?
a. viscosity of a gas decreases with increase in temperature of gas
b. viscosity of a gas increases with increase in temperature of gas
c. viscosity of a gas is not affected by change in temperature of gas
d. viscosity of a gas is unpredictable
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Answer
Explanation
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ANSWER: viscosity of a gas increases with increase in temperature of gas
Explanation:
No explanation is available for this question!
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18) What is kinematics viscosity of a fluid?
a. dynamic viscosity per unit volume of the fluid
b. dynamic viscosity per unit weight of the fluid
c. dynamic viscosity per unit density of the fluid
d. none of the above
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Answer
Explanation
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ANSWER: dynamic viscosity per unit density of the fluid
Explanation:
No explanation is available for this question!
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19) The heat transfer is largely governed by conduction from the surface of the fluid, when
a. the velocity of the fluid is high
b. the velocity of the fluid is small
c. the velocity of the fluid is small as well as high
d. none of the above
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20) Generally, thermal conductivity of liquids is
a. very high
b. very small
c. varies from very small to very high
d. unpredictable
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21) The emissive power of a body depends upon
a. temperature of the body
b. characteristics of the surface of the body
c. both a. and b.
d. none of the above
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22) At a given temperature if wavelengths are changed, the quality of radiation per unit wavelength
a. will always be constant
b. will also be changed
c. will be changed sometimes but sometimes be constant
d. unpredictable
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23) What is the relation between temperature of a body and the wavelength of its emitted radiation at its maximum emissive power?
a. as temperature of a body increases the wavelength of its emitted radiation also increases at its maximum emissive power
b. as temperature of a body increases the wavelength of its emitted radiation decreases at its maximum emissive power
c. as temperature of a body increases the wavelength of its emitted radiation does not change only at its maximum emissive power
d. none of the above
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Answer
Explanation
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ANSWER: as temperature of a body increases the wavelength of its emitted radiation decreases at its maximum emissive power
Explanation:
No explanation is available for this question!
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24) Which of the following relation is correct for the radiation?
a. [Incident Radiation] + [Absorbed Radiation] = [Reflected Radiation] + [Transmitted Radiation]
b. [Incident Radiation] + [Transmitted Radiation] = [Reflected Radiation] + [Absorbed Radiation]
c. [Incident Radiation] = [Reflected Radiation] + [Absorbed Radiation] + [Transmitted Radiation]
d. [Absorbed Radiation] = [Reflected Radiation] + [Transmitted Radiation] + [Incident Radiation]
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Answer
Explanation
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ANSWER: [Incident Radiation] = [Reflected Radiation] + [Absorbed Radiation] + [Transmitted Radiation]
Explanation:
No explanation is available for this question!
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25) What is the relation between reflectivity (ρ), absorptivity (α) and transmissivity (τ)?
a. ρ – α + τ = 1
b. ρ + α – τ = 1
c. ρ + α + τ = 1
d. ρ – α – τ = 1
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26) What is the opaque body?
a. the body which does not reflect radiation
b. the body which does not absorb radiation
c. the body which does not transmit radiation
d. all of the above
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27) What is diffuse reflection of radiation?
a. the reflection of radiation on a rough surface which occurs in all directions
b. the reflection of radiation on a rough surface which occurs in a single direction
c. the reflection of radiation on a smooth surface
d. none of the above
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Answer
Explanation
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ANSWER: the reflection of radiation on a rough surface which occurs in all directions
Explanation:
No explanation is available for this question!
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28) The reflection in which the angle of incident is equal to the angle of reflection is called as
a. regular reflection
b. specular reflection
c. both a. and b.
d. none of the above
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29) The values of reflectivity (ρ), absorptivity (α) and transmissivity (τ) of a body are depend upon
a. material of the body
b. surface condition of the body
c. wavelength of radiation
d. all of the above
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30) Generally, the convection heat transfer coefficient in drop-wise condensation is
a. lower than the convection heat transfer coefficient in film condensation
b. higher than the convection heat transfer coefficient in film condensation
c. equal to the convection heat transfer coefficient in film condensation
d. unpredictable
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Answer
Explanation
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ANSWER: higher than the convection heat transfer coefficient in film condensation
Explanation:
No explanation is available for this question!
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31) Surface coating is suitable to maintain
a. drop-wise condensation
b. film condensation
c. both drop-wise and film condensation
d. none of the above
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32) Which theory is widely used to determine the heat transfer coefficient for film condensation on surfaces?
a. Reynold's theory
b. Grashof's theory
c. Nusselt's theory
d. Prandtl's theory
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33) In a film condensation, the vertical plate temperature should be
a. more than the saturation temperature of the vapour (Ts)
b. less than the saturation temperature of the vapour (Ts)
c. equal to the saturation temperature of the vapour (Ts)
d. none of the above
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Answer
Explanation
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ANSWER: less than the saturation temperature of the vapour (Ts)
Explanation:
No explanation is available for this question!
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34) According to the Nusselt's theory, to determine the heat transfer coefficient for film condensation on surfaces,
a. the vapour should be pure, dry and saturated
b. the condensate flow should be laminar
c. heat transfer should be at steady state
d. all of the above
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