Related Questions

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
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 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
The absorptivity of a body is equal to its emissivity
A At a particular temperature
B For circular bodies
C Under thermal equilibrium
D None of these
Depending on the radiating properties, a body will be opaque when
A p = 0, x = 0 and a = 1
B p = 1, x = 0 and a = 0
C p = 0, x = 1 and a = 0
D x = 0, a + p = 1
Absorptivity and refletivity of a perfect black body are respectively
A 1 and 0
B 0 and 1
C 1 and $$\infty $$
D 0 and 0.5
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
A α = 1; ε ≠ 1
B α ≠ 1, ε = 1
C α ≠ 1, ε ≠ 1
D α = 1; ε = 1
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
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

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