Free convection flow depends on

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Free convection flow depends on

A. Density

B. Coefficient of viscosity

C. Gravitational force

D. All of these

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Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

A. Electric heater

B. Steam condenser

C. Boiler

D. Refrigerator condenser coils

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Heat transfer in liquid and gases takes place by

A. Conduction

B. Convection

C. Radiation

D. Conduction and convection

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Temperature of steam at around 540°C can be measured by

A. Thermometer

B. Thermistor

C. Thermocouple

D. None of these

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The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity)

A. Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁)

B. Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)]

C. Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁)

D. Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁)

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The value of the wave length for maximum emissive power is given by

A. Kirchhoff's law

B. Stefan's law

C. Wines law

D. Planck's law

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In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in

A. Parallel flow

B. Counter flow

C. Cross flow

D. All of these

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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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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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The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called

A. First law of thermodynamics

B. Newton's law of cooling

C. Newton's law of heating

D. Stefan's law

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Absorptivity of a body will be equal to its emissivity

A. At all temperatures

B. At one particular temperature

C. When system is under thermal equilibrium

D. At critical temperature

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In free convection heat transfer, Nusselt number is function of

A. Grashoff number and Reynold number

B. Grashoff number and Prandtl number

C. Prandtl number and Reynold number

D. Grashoff number, Prandtl number and Reynold number

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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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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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Thermal conductivity of a material may be defined as the

A. Quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1°C

B. Quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1°C

C. Heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces

D. All of the above

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Heat flows from one body to other when they have

A. Different heat contents

B. Different specific heat

C. Different atomic structure

D. Different temperatures

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Wiens law states that the wave length corresponding to ________ is proportional to the absolute temperature.

A. Minimum energy

B. Maximum energy

C. Both (A) and (B)

D. None of these

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The insulation ability of an insulator with the presence of moisture would

A. Increase

B. Decrease

C. Remain unaffected

D. May increase/decrease depending on temperature and thickness of insulation

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Upto the critical radius of insulation,

A. Added insulation will increase heat loss

B. Added insulation will decrease heat loss

C. Convective heat loss will be less than conductive heat loss

D. Heat flux will decrease

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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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Thermal diffusivity of a substance is

A. Directly proportional to the thermal conductivity

B. Inversely proportional to density of substance

C. Inversely proportional to specific heat

D. All of the above

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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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The time constant of a thermocouple is

A. The time taken to attain the final temperature to be measured

B. The time taken to attain 50% of the value of initial temperature difference

C. The time taken to attain 63.2% of the value of initial temperature difference

D. Determined by the time taken to reach 100°C from 0°C

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The highest thermal diffusivity is of

A. Iron

B. Lead

C. Concrete

D. Wood

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The rate of energy transferred by convection to that by conduction is called

A. Stanton number

B. Nusselt number

C. Biot number

D. Peclet number

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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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Heat conducted through per unit area and unit thick face per unit time when temperature difference between opposite faces is unity, is called

A. Thermal resistance

B. Thermal coefficient

C. Temperature gradient

D. Thermal conductivity

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The value of Prandtl number for air is about

A. 0.1

B. 0.3

C. 0.7

D. 1.7

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Conduction is a process of heat transfer

A. From one particle of the body to another without the actual motion of the particles

B. From one particle of the body to another by the actual motion of the heated particles

C. From a hot body to a cold body, in a straight line, without affecting the intervening medium

D. None of the above

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Which of the following would lead to a reduction in thermal resistance?

A. In conduction, reduction in the thickness of the material and an increase in thermal conductivity.

B. In convection, stirring of the fluid and cleaning the heating surface.

C. In radiation, increasing the temperature and reducing the emissivity.

D. All of the above

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Thermal conductivity of solid metals with rise in temperature normally

A. Increases

B. Decreases

C. Remain constant

D. May increase or decrease depending on temperature

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Accepted Answer

D. All of these

Free convection flow depends on

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Show all Heat & Mass Transfer MCQ

Related Questions

Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

Heat transfer in liquid and gases takes place by

Temperature of steam at around 540°C can be measured by

The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity)

The value of the wave length for maximum emissive power is given by

In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in

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

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

The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called

Absorptivity of a body will be equal to its emissivity

In free convection heat transfer, Nusselt number is function of

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

Unit of thermal conductivity in S.I. units is

Thermal conductivity of a material may be defined as the

Heat flows from one body to other when they have

Wiens law states that the wave length corresponding to ________ is proportional to the absolute temperature.

The insulation ability of an insulator with the presence of moisture would

Upto the critical radius of insulation,

Film coefficient is defined as Inside diameter of tube

Thermal diffusivity of a substance is

Total heat is the heat required to

The time constant of a thermocouple is

The highest thermal diffusivity is of

The rate of energy transferred by convection to that by conduction is called

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)

Heat conducted through per unit area and unit thick face per unit time when temperature difference between opposite faces is unity, is called

The value of Prandtl number for air is about

Conduction is a process of heat transfer

Which of the following would lead to a reduction in thermal resistance?

Thermal conductivity of solid metals with rise in temperature normally

Also checkout

Free convection flow depends on

Correct Answer :

Show all Heat & Mass Transfer MCQ

Related Questions

Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

Heat transfer in liquid and gases takes place by

Temperature of steam at around 540°C can be measured by

The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity)

The value of the wave length for maximum emissive power is given by

In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in

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

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

The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called

Absorptivity of a body will be equal to its emissivity

In free convection heat transfer, Nusselt number is function of

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

Unit of thermal conductivity in S.I. units is

Thermal conductivity of a material may be defined as the

Heat flows from one body to other when they have

Wiens law states that the wave length corresponding to ________ is proportional to the absolute temperature.

The insulation ability of an insulator with the presence of moisture would

Upto the critical radius of insulation,

Film coefficient is defined as Inside diameter of tube

Thermal diffusivity of a substance is

Total heat is the heat required to

The time constant of a thermocouple is

The highest thermal diffusivity is of

The rate of energy transferred by convection to that by conduction is called

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)

Heat conducted through per unit area and unit thick face per unit time when temperature difference between opposite faces is unity, is called

The value of Prandtl number for air is about

Conduction is a process of heat transfer

Which of the following would lead to a reduction in thermal resistance?

Thermal conductivity of solid metals with rise in temperature normally

Also checkout

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)