Heat and Thermal ExpansionHard
Question
The emissive of a black body at T = 200 K is 100 Watt/m2. Consider a body B of area A = 10m2, coefficient of reflectivity r = 0.3 and coefficient of transmission t = 0.5 its temperature is 300 K. Then which of the following is incorrect :-
Options
A.The emissive power of B is 20 W/m2
B.The emissive power of B is 200 W/m2
C.The power emitted by B is 200 Watt
D.The emissivity of B is = 0.2
Solution
Ans(A)
For body A
P = σAT4
= 100 = σ × 3004
For body B
= (σT4) ∈ = (1 - 0.5 - 0.3) × [σ × 3004]
= 0.2 × 100 = 20W/m2
For body A
P = σAT4
= 100 = σ × 3004For body B
= (σT4) ∈ = (1 - 0.5 - 0.3) × [σ × 3004]= 0.2 × 100 = 20W/m2
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