A grey body is one whose absorptivity

A Varies with temperature
B Varies with wavelength of the incident ray
C Is equal to its emissivity
D Does not vary with temperature and. wavelength of the incident ray

Correct Answer: Does not vary with temperature and. wavelength of the incident ray

A grey body is a body (object) that emits radiation at each wavelength in a constant ratio less than unity to that emitted by a black body at the same temperatures.
A grey body is a physical body whose absorptivity of a surface does not vary with variation in temperature and wavelength of the incident radiation.
Bissoy MCQ
#Mechanical Engineering #Heat And Mass Transfer

Related Questions

Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity?
A Aluminium foil
B Refractory bricks
C Iron plate
D Coke breeze
Absorptivity of a grey body varies with the
A Wavelength of the incident ray
B Temperature
C Both A & B
D Neither A nor B
The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.
A Increases
B Decreases
C Remains constant
D May increase or decrease ; depends on the material
There are five persons sitting on a bench. Blue eyed lady sitting in the middle is my mother. At the extreme left, the man with grey hair is my maternal uncle. Lady sitting at the extreme right is having a pimple on her nose and is the wife of person who is sitting between blue eyed lady and grey haired man and has a pointed nose. A lady having marks on her face is the younger sister of the blue eyed lady and sitting on the remaining fifth place. The person having a pointed nose is the son of the blue eyed lady. What is the lady having marks on her face to the man sitting at extreme left ?
A Wife
B Maternal Aunt
C Sister
D Sister-in-law
Addition of small amount of __________ to grey cast iron is done to produce nodular grey cast iron.
A Manganese
B Phosphorous
C Magnesium
D Chromium
A body is called grey if the monochromatic emissivity of the body is
A Zero
B Unity
C Same for all wavelengths
D Different for all wavelengths
When α is absorptivity, ρ is reflectivity and τ is transmissivity, then for a diathermanous body,
A α = 1, ρ = 0 and τ = 0
B α = 0, ρ = 1 and τ = 0
C α = 0, ρ = 0 and τ = 1
D α + ρ = 1 and τ = 0
The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.
A Wavelength of radiation
B Nature of the body
C Temperature of the body
D None of these
As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the
A Temperature of the body only
B Wavelength of monochromatic radiation
C Both A and B
D Nature of material of body
Absorptivity of a body will be equal to its emissivity
A At all temperatures
B At one particular temperature
C When system is under thermal equilibrium
D At critical temperature

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