A. 0.5
B. 1
C. 0
D. 2
Related Mcqs:
- Absorptivity and reflectivity of a perfect black body are respectively _______________?
A. 1 and 0
B. 0 and 1
C. 1 and ∞
D. 0 and 0.5 - 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 - 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 - The absorptivity of a grey body at a given temperature _____________ with increasing wavelength of radiation?
A. Increases
B. Decreases
C. Remain constant
D. May increase or decrease; depends on the material - What is the absorptivity of a black body?
A. 1
B. 0
C. 0.78
D. 0.95 - The ratio of total radiating power to the absorptivity of the body depends upon the _____________ as per Kirchoff‟s law?
A. Wavelength of radiation
B. Nature of the body
C. Temperature of the body
D. None of these - As per Kirchoff‟s 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 - Which of the following is generally considered as opaque surface towards radiations ?
A. Gases
B. Solids
C. Liquids
D. Both B. and C. - “The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium”. This is ______________ law?
A. Kirchoff’s
B. Planck’s
C. Wien’s displacement
D. Stefan-Boltzmann - Which of the following has the minimum absorptivity ?
A. Aluminium foil
B. Coal dust
C. Refractory bricks
D. Iron plates
