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Mechanical Engineering · Q47

Heat And Mass Transfer

Engineering and GATE · Mechanical Engineering · question 47

Q47

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
Answer
D.
α + ρ = 1 and τ = 0

Answer: Option C

Solution

Answer: Option C
Solution:
Diathermanous body is a body which transmits all the incident radiation without absorbing or reflecting.
(A body with transmitivity 1, reflectivity 0 and absorptivity 0) Air, up to certain extent can be considered as the diathermanous body because, it transmits all the radiation without hearing itself.