This set of Heat Transfer Multiple Choice Questions & Answers (MCQs) focuses on “Black Body”.
1. Radiation heat transfer is characterized by
a) Due to bulk fluid motion, there is transport of energy
b) Thermal energy transfer as vibrational energy in the lattice structure of the material
c) Movement of discrete packets of energy as electromagnetic waves
d) There is circulation of fluid by buoyancy effects
Explanation: EM waves is characterized by radiant heat transfer.
2. Which is true regarding radiation?
a) Radiation travels only in medium
b) Radiation travels without any medium
c) Radiation travels in medium but sometimes without medium
d) Radiation travels in medium or without medium
Explanation: It is true that radiation travels in medium or without medium.
3. Radiation exchange occurs in
Explanation: It occurs more effectively only in vacuum.
4. Energy released by a radiating surface is not continuous but is in the form of successive and separate packets of energy called
Explanation: The photons are propagated through space as rays.
5. The electromagnetic waves are emitted as a result of
(i) Vibrational movement
(ii) Rotational movement
(iii)Atomic or sub-atomic particles comprising the matter
Identify the correct statement
a) 1 and 2
b) 2 and 3
c) 1 and 3
d) 1, 2 and 3
Explanation: The emission occurs when the body is excited by an oscillating electrical signal.
6. Thermal radiations occur in the portion of electromagnetic spectrum between the wavelengths
a) 10 -2 to 10 -4 micron
b) 10 -1 to 10 -2 micron
c) 0.1 to 10 2 micron
d) 10 -2 micron onwards
Explanation: The radiation waves propagates with the speed of light, and their wavelength ranges from 0.1 to 100 micron meter.
7. A perfectly black body
a) Absorbs all the incident radiation
b) Allow all the incident radiation to pass through it
c) Reflects all the incident radiation
d) Has its surface coated with lamp black or graphite
Explanation: A black body is a perfect emitter and absorber.
8. What is the wavelength band for cosmic rays?
a) Up to 45 * 10 -7 micron meter
b) Up to 23 * 10 -7 micron meter
c) Up to 19 * 10 -7 micron meter
d) Up to 4 * 10 -7 micron meter
Explanation: This is its maximum wavelength.
9. For a prescribed wavelength a black body radiates how much energy at the temperature of body?
Explanation: A black body neither reflects nor transmits any amount of incident radiations.
10. “Radiation emitted by a black surface is a function of wavelength and temperature but is independent of direction”. Choose the correct answer
Explanation: The black body is a diffused emitter.
Sanfoundry Global Education & Learning Series – Heat Transfer.
To practice all areas of Heat Transfer, here is complete set of 1000+ Multiple Choice Questions and Answers.