Introduction to Heat Transfer: Learn the Basics of Heat Transfer

Question 1

Which heat transfer mode involves direct energy transfer between molecules in contact?

Accepted Answer

Conduction

Answer

Convection

Answer

Radiation

Answer

Advection

Question 2

Which of the following is NOT a fundamental mode of heat transfer?

Accepted Answer

Condensation

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 3

Which of the following statements about heat transfer is **false**?

Accepted Answer

Heat transfer is always irreversible.

Answer

Heat transfer is the movement of thermal energy from one region to another.

Answer

Heat transfer can occur by conduction, convection, or radiation.

Answer

Heat always flows from a hotter region to a colder region.

Question 4

Which of the following is NOT a fundamental mode of heat transfer?

Accepted Answer

Boiling

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 5

Which mode of heat transfer occurs when a fluid flows over a surface?

Accepted Answer

Convection

Answer

Conduction

Answer

Radiation

Answer

Advection

Question 6

Which characteristic defines a composite wall in heat transfer?

Accepted Answer

Comprises multiple layers of materials with varying thermal conductivities

Answer

Consists of a single material with uniform thermal conductivity

Answer

Always exceeds the thickness of a non-composite wall

Answer

Serves exclusively as an insulating barrier

Question 7

In heat transfer, transmissivity refers to:

Accepted Answer

The proportion of incident radiation that passes through a medium without absorption or reflection.

Answer

The rate of heat flow through a material.

Answer

The ability of a material to emit radiation.

Question 8

What is the definition of the convective heat transfer coefficient?

Accepted Answer

It relates convective heat transfer to temperature difference and surface area.

Answer

It is the ratio of the Nusselt number to the Reynolds number.

Answer

It is the ratio of the Reynolds number to the Prandtl number.

Answer

It is the ratio of the Grashof number to the Reynolds number.

Question 9

In heat transfer, what is the primary purpose of a heat exchanger?

Accepted Answer

Increase surface area for heat transfer between fluids

Answer

Reduce pressure drop in a fluid flow system

Answer

Generate electricity from heat

Answer

Store thermal energy

Question 10

What is the term for the ratio of thermal radiation emitted by a body to that emitted by a blackbody at the same temperature?

Accepted Answer

Emissivity

Answer

Absorptivity

Answer

Reflectivity

Answer

Transmissivity

Question 11

Which parameter does NOT directly influence the convective heat transfer coefficient?

Accepted Answer

Heat flux

Answer

Fluid viscosity

Answer

Surface roughness

Answer

Fluid velocity

Question 12

Newton's law of cooling states that the rate of heat transfer from an object to its surroundings is directly proportional to what factor?

Accepted Answer

Temperature difference between the object and its surroundings

Answer

Surface area of the object

Answer

Thermal conductivity of the object

Answer

Specific heat of the object

Question 13

According to Newton's law of cooling, the rate of heat transfer between an object and its surroundings is directly proportional to:

Accepted Answer

The temperature difference between the object and its surroundings

Answer

The surface area of the object

Answer

The density of the object

Question 14

Which of the following is NOT a fundamental mode of heat transfer?

Accepted Answer

Diffusion

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 15

Which of the following is NOT a fundamental mode of heat transfer?

Accepted Answer

Melting

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 16

Which heat transfer mode involves direct particle contact and transfers kinetic energy between adjacent molecules?

Accepted Answer

Conduction

Answer

Radiation

Answer

Advection

Answer

Convection

Question 17

Which physical property determines a material's capacity to absorb thermal radiation?

Accepted Answer

Absorptivity

Answer

Thermal conductivity

Answer

Specific heat capacity

Question 18

In heat transfer through a solid, which property determines the rate of heat transfer due to conduction?

Accepted Answer

Thermal conductivity

Answer

Density

Answer

Specific heat capacity

Answer

Emissivity

Question 19

In thermal radiation, what does the absorptivity of a surface measure?

Accepted Answer

Absorption of thermal radiation

Answer

Reflection of thermal radiation

Answer

Emission of thermal radiation

Answer

Transmission of thermal radiation

Question 20

Which equation describes the Stefan-Boltzmann law for radiation heat transfer?

Accepted Answer

Q = σA(T^4 - T_0^4)

Answer

Q = σA(T_1 - T_2)

Answer

Q = hA(T_1 - T_2)

Answer

Q = kA(T_1 - T_2)/L

Question 21

Which of the following is not a fundamental mode of heat transfer?

Accepted Answer

Evaporation

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 22

Which of the following is **not** a recognized mode of heat transfer?

Accepted Answer

Diffusion

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 23

In the context of heat transfer, what is the significance of a high thermal conductivity material?

Accepted Answer

It facilitates a higher rate of heat transfer through the material.

Answer

It allows heat to flow more slowly through the material.

Answer

It implies that the material has a lower specific heat capacity.

Question 24

Which surface, a black surface or a gray surface, emits more thermal radiation when both are at the same temperature?

Accepted Answer

Black surface

Answer

Gray surface

Answer

Both surfaces emit the same amount of thermal radiation

Answer

Cannot be determined without additional information

Question 25

What's the difference between heat and thermal energy?

Accepted Answer

Heat is the transfer of energy due to a temperature difference, while thermal energy is the total energy of all particles within an object.

Answer

Thermal energy is the transfer of energy due to a temperature difference, while heat is the total energy of all particles within an object.

Answer

Heat and thermal energy are the same thing.

Answer

Heat is the energy stored in an object, while thermal energy is the energy transferred from one object to another.

Question 26

Radiation heat transfer can occur:

Accepted Answer

Between any two surfaces

Answer

Only through a medium

Answer

Only in a vacuum

Answer

Only between surfaces at different temperatures

Question 27

Which of the following values represents the Stefan-Boltzmann constant?

Accepted Answer

5.67 x 10^-8 W/m^2K^4

Answer

0.1714 W/m^2K^4

Answer

3.14159

Answer

9.81 m/s^2

Question 28

The primary purpose of a heat exchanger is to:

Accepted Answer

Transfer heat between fluids

Answer

Generate heat

Answer

Cool electronic components

Answer

Measure temperature

Question 29

Which of the following is NOT a recognized type of heat exchanger?

Accepted Answer

Thermal Capacitor

Answer

Shell and tube exchanger

Answer

Plate and frame exchanger

Answer

Condenser

Question 30

The overall heat transfer coefficient (U-value) primarily represents:

Accepted Answer

The resistance to heat flow

Answer

The rate of heat transfer per unit area

Answer

The temperature difference between the fluids

Answer

The efficiency of the heat exchanger

Question 31

In designing energy-efficient buildings, how are heat transfer principles utilized?

Accepted Answer

Minimizing heat transfer through building components (e.g., walls, roofs, windows)

Answer

Maximizing heat transfer for indoor air circulation

Answer

Disregarding heat transfer properties when choosing building materials

Answer

Eliminating windows to reduce heat transfer

Question 32

Which of the following is NOT a fundamental mode of heat transfer?

Accepted Answer

Advection

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 33

Which factor does NOT influence the convective heat transfer coefficient?

Accepted Answer

Surface orientation

Answer

Fluid velocity

Answer

Fluid properties

Answer

Surface roughness

Question 34

The Stefan-Boltzmann constant is applied in calculations involving heat transfer by:

Accepted Answer

Radiation

Answer

Conduction

Answer

Convection

Answer

Evaporation

Question 35

The basic equation governing heat conduction is known as:

Accepted Answer

Fourier's law

Answer

Newton's law of cooling

Answer

Stefan-Boltzmann law

Answer

Bernoulli's equation

Question 36

The Stefan-Boltzmann law is used to calculate:

Accepted Answer

Net radiative heat flux

Answer

Emissivity of a surface

Answer

Absorptivity of a surface

Answer

Thermal conductivity of a material

Question 37

Which of the following heat transfer mechanisms is primarily responsible for maintaining a constant body temperature in humans?

Accepted Answer

Evaporation

Answer

Conduction

Answer

Convection

Answer

Radiation

Question 38

The Biot number in heat transfer analysis:

Accepted Answer

Indicates the importance of thermal conduction relative to convection

Answer

Determines the temperature gradient within a body

Answer

Characterizes the thickness of a thermal boundary layer

Answer

Predicts the heat transfer rate

Question 39

Which type of convection is driven by differences in fluid density caused by temperature variations?

Accepted Answer

Natural convection

Answer

Forced convection

Answer

Mixed convection

Answer

Laminar convection

Question 40

The Stefan-Boltzmann law is used to calculate the radiative heat transfer rate between two:

Accepted Answer

Black surfaces

Answer

Gray surfaces

Answer

White surfaces

Answer

Transparent surfaces

Question 41

A heat sink is a device used to:

Accepted Answer

Enhance heat transfer from a surface

Answer

Reduce heat transfer from a surface

Answer

Control the direction of heat flow

Answer

Prevent heat transfer

Question 42

Which of the following materials has the highest thermal conductivity?

Accepted Answer

Copper

Answer

Wood

Answer

Glass

Answer

Rubber

Question 43

The Biot number is used to determine whether:

Accepted Answer

Heat transfer occurs primarily within a solid or at its surface

Answer

Convection or conduction is the dominant mode of heat transfer

Answer

Radiation or convection is the dominant mode of heat transfer

Answer

Fluid flow is laminar or turbulent

Question 44

The Nusselt number is a non-dimensional parameter used to quantify:

Accepted Answer

Convective heat transfer performance

Answer

Radiative heat transfer performance

Answer

Conductive heat transfer performance

Answer

Overall heat transfer performance

Question 45

In natural convection, heat transfer occurs due to:

Accepted Answer

Density differences caused by temperature variations within a fluid

Answer

Forced fluid flow

Answer

Radiation from a heat source

Answer

Thermal conductivity of a material

Question 46

The emissivity of a surface in radiation heat transfer is a measure of its ability to:

Accepted Answer

Emit radiation

Answer

Absorb radiation

Answer

Reflect radiation

Answer

Transmit radiation

Question 47

Which of the following materials has the highest thermal conductivity?

Accepted Answer

Copper

Answer

Wood

Answer

Air

Answer

Water

Question 48

Which of the following is not a mode of heat transfer?

Accepted Answer

Magnetic waves

Answer

Convection

Answer

Radiation

Answer

Conduction

Question 49

The rate of heat flow through a material is directly proportional to its:

Accepted Answer

Thermal conductivity

Answer

Thermal diffusivity

Answer

Density

Answer

Specific heat

Question 50

Heat transfer in a fluid that is in motion occurs by:

Accepted Answer

Convection

Answer

Stefan-Boltzmann law

Answer

Fourier's law

Answer

Diffusion

Question 51

The equation describing heat transfer by radiation is:

Accepted Answer

Stefan-Boltzmann law

Answer

Fourier's law

Answer

Planck's law

Answer

Kirchhoff's law

Question 52

The emissivity of a blackbody is:

Accepted Answer

1

Answer

0.5

Answer

It depends on the temperature

Answer

0

Question 53

Which material has the highest thermal conductivity?

Accepted Answer

Diamond

Answer

Wood

Answer

Rubber

Answer

Water

Question 54

The thermal resistance of a wall is equal to its:

Accepted Answer

Thickness / Thermal conductivity

Answer

Thermal conductivity / Thickness

Answer

Area / Thickness

Question 55

Insulation is used to:

Accepted Answer

Reduce heat transfer

Answer

Regulate temperature

Answer

Increase heat transfer

Question 56

Which of the following is NOT a fundamental mode of heat transfer?

Accepted Answer

Diffusion

Answer

Conduction

Answer

Radiation

Answer

Convection

Question 57

Which of the following is an example of forced convection?

Accepted Answer

Air flowing over a heated plate

Answer

Heat transfer from the sun to the Earth

Answer

Heat transfer from a hot cup of coffee to the surrounding air

Answer

Heat transfer from a hot stove to a pot of water

Question 58

The Stefan-Boltzmann Law describes the rate of heat transfer by:

Accepted Answer

Radiation

Answer

Conduction

Answer

Convection

Answer

All of the above

Question 59

A material with a high thermal conductivity will:

Accepted Answer

Transfer heat more readily

Answer

Transfer heat less readily

Answer

Be a good insulator

Answer

Be a good conductor of electricity

Question 60

The Biot number is a dimensionless parameter that represents the ratio of:

Accepted Answer

Internal resistance to external resistance to heat transfer

Answer

Conduction to convection

Answer

Radiation to convection

Question 61

A lumped capacitance analysis is valid when:

Accepted Answer

The Biot number is much less than 1

Answer

The Biot number is much greater than 1

Answer

The object is in steady-state

Answer

The object is a perfect conductor

Question 62

Which of the following factors would increase the rate of heat transfer by convection?

Accepted Answer

Increasing the velocity of the fluid

Answer

Increasing the viscosity of the fluid

Answer

Decreasing the temperature difference between the surface and the fluid

Answer

Decreasing the surface area of the object

Question 63

A fin is a device that is used to:

Accepted Answer

Enhance heat transfer by increasing the surface area

Answer

Change the mode of heat transfer

Answer

Reduce heat transfer by acting as an insulator

Question 64

Which of the following modes of heat transfer involves the movement of heat through a medium due to the random motion of molecules?

Accepted Answer

Conduction

Answer

Convection

Answer

Radiation

Answer

Diffusion