A. Absorber
B. Emitter
C. Both A. & B.
D. Neither A. nor B.
Related Mcqs:
- While the total emissivity of a perfect black body is unity, the same for a real body is__________________?
A. 0
B. 1
C. > 1
D. Between 0 and 1 - A black body when hot, emits heat radiation of _____________ wavelengths?
A. Small
B. Large
C. All
D. One fixed - The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)?
A. αT
B. α × 1/T
C. α T4
D. Independent of T - 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 - A black body does not ____________ radiation?
A. Absorb or emit
B. Refract
C. Reflect
D. Both B. & C. - Which one gives the monochromatic emissive power for black body radiation ?
A. Planck’s law
B. Kirchhoff’s law
C. Wien’s law
D. Stefan-Boltzmann law - 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 - The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of ‘n’ is exactly 4 for__________________?
A. Black painted bodies only
B. All bodies
C. Polished bodies only
D. A black body - Radiant energy received by a body is proportional to (where, d = the distance between the object emitting radiation and that receiving it.) ?
A. √d
B. d
C. d2
D. d1.5
