Thermodynamics and Heat Transfer MCQs
1. The first law of thermodynamics is based on the principle of:
a) Conservation of mass
b) Conservation of energy
c) Conservation of momentum
d) Conservation of temperature
Answer: b) Conservation of energy
2. The unit of specific heat in the SI system is:
a) Joule
b) Watt
c) Joule per kilogram per Celsius degree (J/kg°C)
d) Watt per meter squared (W/m²)
Answer: c) Joule per kilogram per Celsius degree (J/kg°C)
3. The process in which heat is added to a system while its volume remains constant is called:
a) Isobaric process
b) Isochoric process
c) Isothermal process
d) Adiabatic process
Answer: b) Isochoric process
4. The process in which no heat is exchanged with the surroundings is called:
a) Adiabatic process
b) Isobaric process
c) Isothermal process
d) Isochoric process
Answer: a) Adiabatic process
5. The Carnot cycle is an example of:
a) Ideal gas cycle
b) Reversible cycle
c) Irreversible cycle
d) Rankine cycle
Answer: b) Reversible cycle
6. The efficiency of a Carnot engine depends on:
a) Temperature of the source and sink
b) Pressure of the source and sink
c) Volume of the source and sink
d) Mass of the source and sink
Answer: a) Temperature of the source and sink
7. The second law of thermodynamics states that:
a) Energy cannot be created or destroyed
b) Heat always flows from a hot object to a cold object
c) Entropy of an isolated system always increases
d) Work is the product of force and displacement
Answer: c) Entropy of an isolated system always increases
8. The Clausius statement of the second law of thermodynamics is based on the concept of:
a) Temperature
b) Heat
c) Entropy
d) Energy
Answer: c) Entropy
9. The thermodynamic process in which there is no change in entropy is called:
a) Isothermal process
b) Isentropic process
c) Adiabatic process
d) Isochoric process
Answer: b) Isentropic process
10. The property of a substance that indicates its ability to transmit heat is called:
a) Conductivity
b) Thermal resistance
c) Specific heat
d) Heat capacity
Answer: a) Conductivity
11. Fourier’s law is used to describe:
a) Conduction
b) Convection
c) Radiation
d) All of the above
Answer: a) Conduction
12. The rate of heat transfer by conduction through a material depends on:
a) Temperature difference
b) Material properties
c) Thickness of the material
d) All of the above
Answer: d) All of the above
13. The rate of heat transfer by convection depends on:
a) Temperature difference
b) Surface area
c) Fluid properties
d) All of the above
Answer: d) All of the above
14. The Nusselt number is used in the analysis of:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: b) Convection
15. The Stefan-Boltzmann law describes the relationship between:
a) Temperature and heat capacity
b) Temperature and emissivity
c) Temperature and radiation intensity
d) Temperature and conductivity
Answer: c) Temperature and radiation intensity
16. The process in which heat is transferred by electromagnetic waves is called:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: c) Radiation
17. The color of an object affects its:
a) Conductivity
b) Emissivity
c) Specific heat
d) Heat capacity
Answer: b) Emissivity
18. The U-value (or U-factor) is a measure of:
a) Conductivity
b) Convective heat transfer
c) Radiative heat transfer
d) All of the above
Answer: d) All of the above
19. The heat transfer coefficient depends on:
a) Fluid properties
b) Surface geometry
c) Surface roughness
d) All of the above
Answer: d) All of the above
20. The term “heat exchanger effectiveness” refers to:
a) How efficiently a heat exchanger transfers heat
b) The temperature difference in a heat exchanger
c) The size of a heat exchanger
d) The shape of a heat exchanger
Answer: a) How efficiently a heat exchanger transfers heat
21. The logarithmic mean temperature difference (LMTD) is used in the analysis of:
a) Conduction
b) Convection
c) Radiation
d) Heat exchangers
Answer: d) Heat exchangers
22. The term “thermal conductivity” refers to a material’s ability to:
a) Conduct electricity
b) Conduct heat
c) Conduct light
d) Conduct sound
Answer: b) Conduct heat
23. The thermal diffusivity of a material is given by the ratio of:
a) Thermal conductivity to specific heat
b) Specific heat to thermal conductivity
c) Heat capacity to thermal conductivity
d) Thermal conductivity to heat capacity
Answer: a) Thermal conductivity to specific heat
24. The term “heat capacity” refers to:
a) The amount of heat required to raise the temperature of a substance
b) The rate of heat transfer in a substance
c) The ability of a substance to conduct heat
d) The ability of a substance to store heat
Answer: a) The amount of heat required to raise the temperature of a substance
25. The heat transfer rate through a material is directly proportional to:
a) Temperature difference
b) Material thickness
c) Material conductivity
d) Material density
Answer: a) Temperature difference
26. The thermal resistance of a material is given by the ratio of:
a) Material thickness to thermal conductivity
b) Thermal conductivity to material thickness
c) Material thickness to specific heat
d) Thermal conductivity to specific heat
Answer: a) Material thickness to thermal conductivity
27. The Fourier number is used to characterize:
a) Conductive heat transfer
b) Convective heat transfer
c) Radiative heat transfer
d) All of the above
Answer: a) Conductive heat transfer
28. The Biot number is used to determine the:
a) Convective heat transfer coefficient
b) Conductive heat transfer coefficient
c) Radiative heat transfer coefficient
d) All of the above
Answer: a) Convective heat transfer coefficient
29. The concept of “thermal boundary layer” is associated with:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: b) Convection
30. The Péclet number is used in the analysis of:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: b) Convection
31. The Prandtl number is used in the analysis of:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: b) Convection
32. The term “heat flux” refers to the rate of heat transfer per unit:
a) Volume
b) Area
c) Mass
d) Temperature
Answer: b) Area
33. The concept of “thermal conductivity” is analogous to which electrical property?
a) Resistance
b) Conductance
c) Capacitance
d) Inductance
Answer: b) Conductance
34. The thermal resistance of a material can be decreased by:
a) Decreasing its thickness
b) Decreasing its conductivity
c) Increasing its thickness
d) Increasing its conductivity
Answer: d) Increasing its conductivity
35. The heat transfer coefficient in convection depends on the:
a) Surface area
b) Temperature difference
c) Both surface area and temperature difference
d) Neither surface area nor temperature difference
Answer: c) Both surface area and temperature difference
36. The process of heat transfer in fluids due to the movement of fluid particles is called:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: b) Convection
37. The Newton’s law of cooling relates the rate of heat loss to:
a) Temperature difference
b) Surface area
c) Time
d) All of the above
Answer: a) Temperature difference
38. The term “heat exchanger” is used to transfer heat between:
a) Two solids
b) Two fluids
c) Solid and fluid
d) None of the above
Answer: b) Two fluids
39. The effectiveness of a heat exchanger is defined as:
a) The ratio of actual heat transfer to maximum possible heat transfer
b) The ratio of maximum possible heat transfer to actual heat transfer
c) The ratio of heat capacity to heat transfer rate
d) The ratio of heat transfer rate to heat capacity
Answer: a) The ratio of actual heat transfer to maximum possible heat transfer
40. The thermal conductivity of a material is affected by:
a) Temperature
b) Pressure
c) Density
d) All of the above
Answer: d) All of the above
41. The thermal conductivity of gases generally:
a) Increases with temperature
b) Decreases with temperature
c) Remains constant with temperature
d) Depends on the type of gas
Answer: a) Increases with temperature
42. The process of heat transfer in solids due to molecular motion is called:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: a) Conduction
43. The phenomenon where a material emits radiation when heated is known as:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: c) Radiation
44. The Stefan-Boltzmann constant is used in the calculation of:
a) Conductive heat transfer
b) Convective heat transfer
c) Radiative heat transfer
d) None of the above
Answer: c) Radiative heat transfer
45. The emissivity of a surface is a measure of its:
a) Reflectivity
b) Absorptivity
c) Transmissivity
d) All of the above
Answer: b) Absorptivity
46. The process of transferring heat energy through electromagnetic waves is known as:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: c) Radiation
47. The Stefan-Boltzmann law relates the total energy radiated by a blackbody to its:
a) Area
b) Temperature
c) Density
d) Volume
Answer: b) Temperature
48. The heat transfer by radiation depends on the:
a) Temperature difference
b) Surface area
c) Emissivity
d) All of the above
Answer: d) All of the above
49. The Dittus-Boelter equation is used for the analysis of:
a) Conduction
b) Convection
c) Radiation
d) Advection
Answer: b) Convection
50. The heat transfer through a composite wall can be analyzed using:
a) Fourier’s law
b) Newton’s law of cooling
c) Biot’s law
d) Ohm’s law
Answer: c) Biot’s law