Chauvin Arnoux C.A 1875, User Manual

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Solution 3
Question a
Stefan's law:
P = S ε σ T
4
With ε = 1 because black body
σ = 5.68 x 10
-8
Boltzmann's constant
S = π R
2
surface of a ball
Whence:
T
4
= P/S ε σ => T = 847 °K = 574°C
Question b
Wien's law:
λ
max
T = Constant
= 2 898 µ m.K
Whence:
λ
max
= 2 898/T => λ
max
= 3.42 µ m
Solution 4
Question a
Stefan's law:
P = S ε σ T
4
With ε = 1 because black body
σ = 5.68 x 10
-8
Boltzmann's constant
Whence:
T
4
= P/S ε σ => T = 5,792°K
Question b
Wien's law:
λ
max
T = Constant
= 2,898 µ m.K
Whence:
λ
max
= 2,898/T => λ
max
= 0.5 µ m
We are in visible light, which is why the sun looks yellow to us, etc.
Solution 5
This is a thermographic image of a face with glasses.
We can see that the glasses are colder than the person's face.
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