Heat Transfer MCQ’s – Black Body

1 - Question

Radiation heat transfer is characterized by
a) Due to bulk fluid motion, there is a 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
View Answer Answer: c
Explanation: EM waves is characterized by radiant heat transfer.

2 - Question

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
View Answer Answer: d
Explanation: It is true that radiation travels in medium or without medium.

3 - Question

Radiation exchange occurs in
a) Solid
b) Vacuum
c) Liquid
d) Gas
View Answer Answer: b
Explanation: It occurs more effectively only in vacuum.

4 - Question

Energy released by a radiating surface is not continuous but is in the form of successive and separate packets of energy called
a) Photons
b) Protons
c) Electrons
d) Neutrons
View Answer Answer: a
Explanation: The photons are propagated through space as rays.

5 - Question

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) i and ii
b) ii and iii
c) i and iii
d) i, ii and iii
View Answer Answer: d
Explanation: The emission occurs when the body is excited by an oscillating electrical signal.

6 - Question

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
View Answer Answer: c
Explanation: The radiation waves propagates with the speed of light, and their wavelength ranges from 0.1 to 100 micron meter.

7 - Question

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
View Answer Answer: a
Explanation: A black body is a perfect emitter and absorber.

8 - Question

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
View Answer Answer: d
Explanation: This is its maximum wavelength.

9 - Question

For a prescribed wavelength a black body radiates how much energy at the temperature of body?
a) Maximum
b) Minimum
c) 20%
d) 50%
View Answer Answer: a
Explanation: A black body neither reflects nor transmits any amount of incident radiations.

10 - Question

Radiation emitted by a black surface is a function of wavelength and temperature but is independent of direction.
a) True
b) False
View Answer Answer: a
Explanation: The black body is a diffused emitter.

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