JEE Main - Heat transfer by conduction, convection and radiation Online Test (MCQ Quiz)

1. Which mode of heat transfer does not require a medium?

A) Conduction B) Convection C) Radiation D) Both Conduction and Convection

2. In which of the following states of matter does convection occur most effectively?

A) Solids B) Liquids C) Gases D) Plasma

3. The phenomenon of heat transfer through conduction is most significant in:

A) Vacuum B) Gases C) Liquids D) Solids

4. Which of the following is an example of heat transfer by radiation?

A) Heating of a metal rod from one end to the other B) Boiling of water in a pot C) Warmth of the sun felt on Earth D) Melting of ice by touching it

5. The SI unit of the coefficient of thermal conductivity is:

A) W/mK B) W/(m·K) C) J/(s·m·K) D) All of the above

6. Which material is a poor conductor of heat?

A) Copper B) Aluminum C) Wood D) Silver

7. Convection current is formed due to difference in:

A) Temperature only B) Density only C) Specific heat only D) Temperature and density

8. According to Stefan's Law, the total energy radiated per unit surface area of a black body per unit time is proportional to:

A) T B) T^2 C) T^3 D) T^4

9. A black body at absolute temperature T radiates energy at a rate proportional to:

A) T B) T^2 C) T^3 D) T^4

10. The rate of heat transfer by conduction through a plane wall is given by Fourier's Law: dQ/dt = -kA(dT/dx). Here, A represents:

A) Area of cross-section perpendicular to heat flow B) Area of cross-section parallel to heat flow C) Volume of the material D) Thickness of the wall

11. Which of the following has the highest thermal conductivity?

A) Diamond B) Glass C) Water D) Air

12. When a metal spoon is dipped in hot soup, the heat is transferred to the handle by:

A) Conduction B) Convection C) Radiation D) Evaporation

13. The color of a good absorber of heat is generally:

A) White B) Shiny C) Dull black D) Light colored

14. A thermos flask works on the principle of minimizing heat transfer by:

A) Conduction and Convection B) Conduction and Radiation C) Convection and Radiation D) Conduction, Convection, and Radiation

15. The temperature of a black body is increased, its radiated power:

A) Decreases B) Increases C) Remains the same D) Increases only if the color changes

16. Which of the following is a good thermal insulator?

A) Steel B) Brass C) Rubber D) Aluminum

17. The process of heat transfer in liquids and gases due to the movement of the fluid itself is called:

A) Conduction B) Convection C) Radiation D) Diffusion

18. The emissivity of a perfectly black body is:

A) 0 B) 0.5 C) 1 D) Infinity

19. Wien's displacement law relates the wavelength of maximum spectral radiance of a black body to its:

A) Volume B) Surface area C) Temperature D) Emissivity

20. Which phenomenon is responsible for the formation of land and sea breezes?

A) Conduction B) Convection C) Radiation D) Reflection

21. If the temperature of an object is doubled, the energy radiated per unit time increases by a factor of:

A) 2 B) 4 C) 8 D) 16

22. The R-value of thermal insulation is a measure of:

A) Thermal conductivity B) Thermal resistance C) Thermal capacity D) Thermal diffusivity

23. Which law governs the thermal radiation emitted by a black body?

A) Newton's Law of Cooling B) Stefan-Boltzmann Law C) Wien's Displacement Law D) Kirchhoff's Law of Radiation

24. Heat transfer by radiation is fastest when the medium is:

A) Dense B) Rarefied C) A good conductor D) A good insulator

25. In a convection current, the warmer fluid rises because it is:

A) Denser B) Less dense C) Hotter D) Colder

26. The surface of a good emitter of thermal radiation is also a good:

A) Reflector B) Absorber C) Transmitter D) Conductor

27. Which of the following statements about conduction is FALSE?

A) It occurs in solids, liquids, and gases. B) It requires a temperature gradient. C) It involves the movement of particles from one place to another. D) It is the primary mode of heat transfer in fluids.

28. The thermal conductivity of a material depends on:

A) Its temperature B) Its density C) Its molecular structure D) All of the above

29. During convection, heat is transferred by:

A) Vibrations of molecules B) Movement of the fluid itself C) Electromagnetic waves D) Direct contact of particles

30. The rate of heat radiated by a body is directly proportional to its:

A) Mass B) Volume C) Surface area D) Density

31. Which of the following is NOT a mechanism of heat transfer?

A) Conduction B) Convection C) Radiation D) Evaporation

32. A person feels warmer near a fire due to heat transfer by:

A) Conduction B) Convection C) Radiation D) All of the above

33. The effectiveness of a material as a thermal insulator is measured by its:

A) High thermal conductivity B) Low thermal conductivity C) High specific heat capacity D) Low specific heat capacity

34. In solids, heat is primarily transferred by:

A) Convection B) Radiation C) Conduction D) Advection

35. The phenomenon of a hot air balloon rising is an example of:

A) Conduction B) Convection C) Radiation D) Thermal expansion

36. Which of the following surfaces will emit the maximum thermal radiation at a given temperature?

A) Polished metallic surface B) Dull black surface C) White painted surface D) Shiny silver surface

37. Newton's Law of Cooling states that the rate of cooling of a body is proportional to the:

A) Temperature of the body B) Excess temperature of the body over the surroundings C) Square of the temperature of the body D) Cube of the temperature of the body

38. The heat transfer by conduction in metals is mainly due to the movement of:

A) Free electrons B) Atoms C) Molecules D) Ions

39. Which of the following is a good conductor of heat?

A) Air B) Wood C) Glass D) Iron

40. The primary mode of heat transfer from the Sun to the Earth is:

A) Conduction B) Convection C) Radiation D) None of the above

41. A convection current in a fluid will stop if:

A) The fluid is heated from above B) The fluid is heated from below C) There is no temperature difference D) The fluid is very viscous

42. Which property of a material is most important for its use as a thermal insulator?

A) High density B) Low thermal conductivity C) High specific heat D) High melting point

43. The rate of heat transfer by radiation is independent of:

A) Temperature of the body B) Emissivity of the body C) Surface area of the body D) The medium through which radiation travels

44. Which of the following is an example of heat transfer by convection?

A) Melting of ice B) Heating of a room by a heater C) Sunlight warming the Earth D) Heat moving along a metal rod

45. The thermal resistance of a material is inversely proportional to its:

A) Thickness B) Area C) Thermal conductivity D) All of the above

46. A body at a high temperature will radiate energy at a rate proportional to:

A) Its temperature B) Its temperature squared C) Its temperature cubed D) Its temperature to the fourth power

47. Which type of heat transfer involves the emission of electromagnetic waves?

A) Conduction B) Convection C) Radiation D) Evaporation

48. The phenomenon of boiling water in a pot is primarily due to:

A) Conduction from the bottom to the water B) Convection currents within the water C) Radiation from the heating element D) Evaporation from the surface

49. The Stefan-Boltzmann constant (sigma) has units of:

A) W/(m^2 K^4) B) W/(m K) C) J/(s m^2) D) W/K

50. Which of the following is the most efficient way to transfer heat through a solid?

A) Convection B) Radiation C) Conduction D) It depends on the solid's properties

Heat transfer by conduction, convection and radiation - Online Test

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