Question 1

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

Accepted Answer

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 
E) uNPredictable. 
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 
E) uNPredictable. A

Question 2

Thermal diffusivity of a substance is

Accepted Answer

A) directly proportional to thermal con¬ductivity 
B) inversely proportional to density of substance 
C) inversely proportional to specific heat 
D) all of the above 
E) none of the above. 
A) directly proportional to thermal con¬ductivity 
B) inversely proportional to density of substance 
C) inversely proportional to specific heat 
D) all of the above 
E) none of the above. D

Question 3

All radiations in a black body are

Accepted Answer

A) reflected 
B) refracted 
C) transmitted 
D) absorbed 
E) partly reflected and partly absorbed. 
A) reflected 
B) refracted 
C) transmitted 
D) absorbed 
E) partly reflected and partly absorbed. D

Question 4

The value of the wavelength for maximum emissive power is given by -

Accepted Answer

A) Wien's law 
B) Planck's law 
C) Stefan's law 
D) Fourier's law 
E) Kirchhoff's law. 
A) Wien's law 
B) Planck's law 
C) Stefan's law 
D) Fourier's law 
E) Kirchhoff's law.

Question 5

Joule sec is the unit of

Accepted Answer

A) universal gas constant 
B) kinematic viscosity 
C) thermal conductivity 
D) Planck's constant 
E) none of the above. 
A) universal gas constant 
B) kinematic viscosity 
C) thermal conductivity 
D) Planck's constant 
E) none of the above.

Question 6

The thermal diffusivities for solids are generally

Accepted Answer

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 
E) zerci. 
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 
E) zerci.

Question 7

The unit of Stefan Boltzmann constant is

Accepted Answer

A) watt/cm2 °K 
B) watt/cmm4 °K 
C) watt2/cm °K4 
D) watt/cm2 °K4 
E) watt/cm2 °K2. 
A) watt/cm2 °K 
B) watt/cmm4 °K 
C) watt2/cm °K4 
D) watt/cm2 °K4 
E) watt/cm2 °K2.

Question 8

LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is

Accepted Answer

A) higher 
B) lower 
C) same 
D) depends on the area of heat exchanger 
E) depends on temperature conditions. 
A) higher 
B) lower 
C) same 
D) depends on the area of heat exchanger 
E) depends on temperature conditions.

Question 9

Total emissivity of polished silver compared to black body is

Accepted Answer

A) same 
B) higher 
C) more or less same 
D) very much lower 
E) very much higher. 
A) same 
B) higher 
C) more or less same 
D) very much lower 
E) very much higher.

Question 10

According to Stefan's law, the total radiation from a black body per second per unit area is proportional to

Accepted Answer

A) absolute temperature 
B) T2 
C) T5 
D) t 
E) l/T. 
A) absolute temperature 
B) T2 
C) T5 
D) t 
E) l/T.

Question 11

Log mean temperature difference in case of counter flow compared to parallel flow will be

Accepted Answer

A) same 
B) more 
C) less 
D) depends on other factors 
E) none of the above. 
A) same 
B) more 
C) less 
D) depends on other factors 
E) none of the above.

Question 12

In heat exchangers, degree of approach is defined as the difference between temperatures of

Accepted Answer

A) cold water inlet and outlet 
B) hot medium inlet and outlet 
C) hot medium outlet and cold water inlet 
D) hot medium outlet and cold water outlet 
E) none of the above. 
A) cold water inlet and outlet 
B) hot medium inlet and outlet 
C) hot medium outlet and cold water inlet 
D) hot medium outlet and cold water outlet 
E) none of the above.

Question 13

The concept of overall coefficient of heat transfer is used in case of heat transfer by

Accepted Answer

A) conduction 
B) convection 
C) radiation 
D) conduction and convection 
E) convection and radiation. 
A) conduction 
B) convection 
C) radiation 
D) conduction and convection 
E) convection and radiation.

Question 14

The energy distribution of an ideal reflector at higher temperatures is largely in the range of

Accepted Answer

A) shorter wavelength 
B) longer wavelength 
C) remains same at all wavelengths 
D) wavelength has nothing to do with it 
E) none of the above. 
A) shorter wavelength 
B) longer wavelength 
C) remains same at all wavelengths 
D) wavelength has nothing to do with it 
E) none of the above.

Question 15

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

Accepted Answer

A) Krichoff's law 
B) Stefan's law 
C) Wien' law 
D) Planck's law 
E) Black body law. 
A) Krichoff's law 
B) Stefan's law 
C) Wien' law 
D) Planck's law 
E) Black body law.

Question 16

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

Accepted Answer

A) absolute temperature 
B) square of temperature 
C) fourth power of absolute temperature 
D) fourth power of temperature 
E) cube of absolute temperature. 
A) absolute temperature 
B) square of temperature 
C) fourth power of absolute temperature 
D) fourth power of temperature 
E) cube of absolute temperature.

Question 17

The thermal diffusivities for gases are generally

Accepted Answer

A) more than those for liquids 
B) less than those for liquids 
C) more than those for solids 
D) dependent on the viscosity 
E) same as for the liquids. 
A) more than those for liquids 
B) less than those for liquids 
C) more than those for solids 
D) dependent on the viscosity 
E) same as for the liquids.

Question 18

According of Kirchhoff's law,

Accepted Answer

A) radiant heat is proportional to fourth power of absolute temperature 
B) emissive power depends on temperature 
C) emissive power and absorptivity are constant for all bodies 
D) ratio of emissive power to absorptive power is maximum for perfectly black body 
E) ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body. 
A) radiant heat is proportional to fourth power of absolute temperature 
B) emissive power depends on temperature 
C) emissive power and absorptivity are constant for all bodies 
D) ratio of emissive power to absorptive power is maximum for perfectly black body 
E) ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.

Question 19

Which of the following property of air does not increase with rise in temperature

Accepted Answer

A) thermal conductivity 
B) thermal diffusivity 
C) density 
D) dynamic viscosity 
E) kuiematic viscosity. 
A) thermal conductivity 
B) thermal diffusivity 
C) density 
D) dynamic viscosity 
E) kuiematic viscosity.

Question 20

Fourier's law of heat conduction is valid for

Accepted Answer

A) one dimensional cases only 
B) two dimensional cases only 
C) three dimensional cases only 
D) regular surfaces having non-uniform temperature gradients 
E) irregular surfaces. 
A) one dimensional cases only 
B) two dimensional cases only 
C) three dimensional cases only 
D) regular surfaces having non-uniform temperature gradients 
E) irregular surfaces.

Exam 9: Heat Transfer and Thermal Properties: Part A

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

Thermal diffusivity of a substance is

All radiations in a black body are

The value of the wavelength for maximum emissive power is given by -

Joule sec is the unit of

The thermal diffusivities for solids are generally

The unit of Stefan Boltzmann constant is

LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is

Total emissivity of polished silver compared to black body is

According to Stefan's law, the total radiation from a black body per second per unit area is proportional to

Log mean temperature difference in case of counter flow compared to parallel flow will be

In heat exchangers, degree of approach is defined as the difference between temperatures of

The concept of overall coefficient of heat transfer is used in case of heat transfer by

The energy distribution of an ideal reflector at higher temperatures is largely in the range of

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

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

The thermal diffusivities for gases are generally

According of Kirchhoff's law,

Which of the following property of air does not increase with rise in temperature

Fourier's law of heat conduction is valid for

Thermal Conductivity and Heat Transfer

Heat Transfer and Thermal Conductivity: Part A

Heat Transfer and Thermal Conductivity: Part B

Heat Transfer and Thermal Conductivity: Part C

Heat Transfer and Evaporator

Heat Transfer and Heat Exchangers: Part A

Heat Transfer and Heat Exchangers: Part B

Heat Transfer and Crystallisation

Heat Transfer and Thermal Properties: Part A

Heat Transfer and Thermal Properties: Part B

Heat Exchangers and Condensation

Thermal Properties and Processes

Concepts in Heat Transfer

Components of Radiation From Flames

Heat Transfer and Thermodynamics

Heat Transfer Processes, Thermometers, and Evaporators

Heat Transfer Mechanisms in a Spaced Plate System

Heat Transfer and Evaporation

Understanding the Dominant Mechanism of Heat Transfer

Heat Transfer and Fluid Mechanics

Heat Transfer and Boiling Point Elevation in Solutions

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