Heat Transfer MCQs

1.According to Wien's displacement law, the wavelength at which a blackbody emits maximum radiation is directly related to which of the following?

2.Under what condition, based on radiative characteristics, is a material considered opaque?

3.Under which condition based on radiative characteristics does an object appear white?

4.Which principle states that the ratio of a body's emissive power to its absorptive power is constant for all materials and equals the emissive power of an ideal black body?

5.How do the thermal diffusivities of solids typically compare to those of liquids and gases?

Lower than the thermal diffusivity of gasesSmaller than that of liquidsHigher than those of both liquids and gasesApproximately equal to the values for liquids and gasesNone of the above

6.According to Stefan's law, the total energy radiated per second per unit area by a black body is directly proportional to which of the following?

The absolute temperatureThe square of the temperature (T²)The fifth power of the temperature (T⁵)The fourth power of the temperature (T⁴)The reciprocal of the temperature (1/T)

7.Under which conditions related to radiative properties is a body considered black?

8.The total emissive power refers to the total radiation energy emitted by a black body per unit of what?

9.A thermally transparent material reflects 40% of the incoming radiant energy on its surface. If the material's transmissivity is 0.15, what is the emissivity of its surface?

10.Which factors influence the emissive power of a material?

11.What term describes the ratio of energy absorbed by a surface to the total energy incident upon it?

12.The quantity of radiation emitted primarily depends on which of the following factors?

the physical properties of the objectthe object's temperaturethe characteristics of the object's surfaceall the factors mentioned abovenone of these factors

13.Under which condition does a body's absorptivity equal its emissivity?

At every temperatureOnly at a specific temperatureWhen the system reaches thermal equilibriumAt the critical temperatureFor a highly reflective surface

14.Under what conditions related to radiative properties does a body become transparent?

15.Two parallel plates separated by 150 mm are kept at temperatures of 1000°C and 70°C respectively. Which mode of heat transfer predominantly occurs between them?

Heat Transfer MCQs

About this subject