A grey body is one whose absorptivity

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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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The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as

A. Conduction

B. Free convection

C. Forced convection

D. Radiation

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The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law.

A. Equal to

B. Directly proportional to

C. Inversely proportional to

D. None of these

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Total heat is the heat required to

A. Change vapour into liquid

B. Change liquid into vapour

C. Increase the temperature of a liquid or vapour

D. Convert water into steam and superheat it

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Unit of thermal conductivity in S.I. units is

A. J/m² sec

B. J/m °K sec

C. W/m °K

D. Option (B) and (C) above

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Depending on the radiating properties, a body will be black when

A. P = 0, x = 0 and a = 1

B. P= 1, T = 0 and a = 0

C. P = 0, x = 1 and a = 0

D. X = 0, a + p = 0 Where a = absorptivity, p = reflectivity, X = transmissivity.

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When α is absorptivity, ρ is reflectivity and τ is transmissivity, then for a diathermanous body,

A. α = 1, ρ = 0 and τ = 0

B. α = 0, ρ = 1 and τ = 0

C. α = 0, ρ = 0 and τ = 1

D. α + ρ = 1 and τ = 0

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Stefan Boltzmann law is applicable for heat transfer by

A. Conduction

B. Convection

C. Radiation

D. Conduction and radiation combined

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Emissivity of a white polished body in comparison to a black body is

A. Higher

B. Lower

C. Same

D. Depends upon the shape of body

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Pick up the wrong case. Heat flowing from one side to other depends directly on

A. Face area

B. Time

C. Thickness

D. Temperature difference

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In case of liquids and gases, the heat transfer takes place according to

A. Conduction

B. Convection

C. Radiation

D. None of these

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Heat is closely related with

A. Liquids

B. Energy

C. Temperature

D. Entropy

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The emissive power of a body depends upon its

A. Temperature

B. Wave length

C. Physical nature

D. All of the above

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Thermal conductivity of water ________ with rise in temperature.

A. Remain same

B. Decreases

C. Increases

D. May increase or decrease depending upon temperature

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

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

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

A. Shorter wavelength

B. Longer wavelength

C. Remain same at all wavelengths

D. Wavelength has nothing to do with it

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The unit of Stefan Boltzmann constant is

A. Watt/cm² °K

B. Watt/cm4 °K

C. Watt²/cm °K⁴

D. Watt/cm² °K⁴

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

A. Absolute temperature

B. Square of the absolute temperature

C. Cube of the absolute temperature

D. Fourth power of the absolute temperature

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The ratio of Nusselt number and the product of Reynold's number and Prandtl number is equal to

A. Stanton number

B. Biot number

C. Peclet number

D. Grashoff number

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Thermal conductivity of water at 20°C is of the order of

A. 0.1

B. 0.23

C. 0.42

D. 0.51

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The logarithmic mean temperature difference (t_m) is given by (where Δt₁ and Δt₂ are temperature differences between the hot and cold fluids at entrance and exit)

A. t_m = (Δt₁ - Δt₂)/ log_e (Δt₁/Δt₂)

B. t_m = log_e (Δt₁/Δt₂)/ (Δt₁ - Δt₂)

C. t_m = t_m = (Δt₁ - Δt₂) log_e (Δt₁/Δt₂)

D. t_m = log_e (Δt₁ - Δt₂)/ Δt₁/Δt₂

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The ratio of surface convection resistance to the internal conduction resistance is known as

A. Grashoff number

B. Biot number

C. Stanton number

D. Prandtl number

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The thermal diffusivities for solids are generally

A. Less than those for gases

B. Less than those for liquids

C. More than those for liquids and gases

D. More or less same as for liquids and gases

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Which of the following has least value of conductivity?

A. Glass

B. Water

C. Plastic

D. Air

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A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be

A. k₁ k₂

B. (k₁ + k₂)

C. (k₁ + k₂)/ k₁ k₂

D. 2 k₁ k₂/ (k₁ + k₂)

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Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)

A. k. A. (dT/dx)

B. k. A. (dx/dT)

C. k. (dT/dx)

D. k. (dx/dT)

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The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as

A. Emissivity

B. Transmissivity

C. Reflectivity

D. Intensity of radiation

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The radiation emitted by a black body is known as

A. Black radiation

B. Full radiation

C. Total radiation

D. All of these

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According to Wien's law, the wavelength corresponding to maximum energy is proportion to

A. Absolute temperature (T)

B. I²

C. F

D. T

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Film coefficient is defined as Inside diameter of tube

A. Equivalent thickness of film

B. Thermal conductivity Equivalent thickness of film Specific heat × Viscosity

C. Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity

D. Film coefficient × Inside diameter Thermal conductivity

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Which of the following is the case of heat transfer by radiation?

A. Blast furnace

B. Heating of building

C. Cooling of parts in furnace

D. Heat received by a person from fireplace

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Accepted Answer

C. Is equal to its emissivity

A grey body is one whose absorptivity

Correct Answer :

Show all Heat & Mass Transfer MCQ

Related Questions

The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as

The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law.

Total heat is the heat required to

Unit of thermal conductivity in S.I. units is

Depending on the radiating properties, a body will be black when

When α is absorptivity, ρ is reflectivity and τ is transmissivity, then for a diathermanous body,

Stefan Boltzmann law is applicable for heat transfer by

Emissivity of a white polished body in comparison to a black body is

Pick up the wrong case. Heat flowing from one side to other depends directly on

In case of liquids and gases, the heat transfer takes place according to

Heat is closely related with

The emissive power of a body depends upon its

Thermal conductivity of water ________ with rise in temperature.

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

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

The unit of Stefan Boltzmann constant is

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

The ratio of Nusselt number and the product of Reynold's number and Prandtl number is equal to

Thermal conductivity of water at 20°C is of the order of

The logarithmic mean temperature difference (t_m) is given by (where Δt₁ and Δt₂ are temperature differences between the hot and cold fluids at entrance and exit)

The ratio of surface convection resistance to the internal conduction resistance is known as

The thermal diffusivities for solids are generally

Which of the following has least value of conductivity?

A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be

The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as

The radiation emitted by a black body is known as

According to Wien's law, the wavelength corresponding to maximum energy is proportion to

Film coefficient is defined as Inside diameter of tube

Which of the following is the case of heat transfer by radiation?

Also checkout

A grey body is one whose absorptivity

Correct Answer :

Show all Heat & Mass Transfer MCQ

Related Questions

The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as

The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law.

Total heat is the heat required to

Unit of thermal conductivity in S.I. units is

Depending on the radiating properties, a body will be black when

When α is absorptivity, ρ is reflectivity and τ is transmissivity, then for a diathermanous body,

Stefan Boltzmann law is applicable for heat transfer by

Emissivity of a white polished body in comparison to a black body is

Pick up the wrong case. Heat flowing from one side to other depends directly on

In case of liquids and gases, the heat transfer takes place according to

Heat is closely related with

The emissive power of a body depends upon its

Thermal conductivity of water ________ with rise in temperature.

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

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

The unit of Stefan Boltzmann constant is

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

The ratio of Nusselt number and the product of Reynold's number and Prandtl number is equal to

Thermal conductivity of water at 20°C is of the order of

The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit)

The ratio of surface convection resistance to the internal conduction resistance is known as

The thermal diffusivities for solids are generally

Which of the following has least value of conductivity?

A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be

The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as

The radiation emitted by a black body is known as

According to Wien's law, the wavelength corresponding to maximum energy is proportion to

Film coefficient is defined as Inside diameter of tube

Which of the following is the case of heat transfer by radiation?

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The logarithmic mean temperature difference (t_m) is given by (where Δt₁ and Δt₂ are temperature differences between the hot and cold fluids at entrance and exit)