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Naddika [18.5K]
3 years ago
9

The spectral distribution of the radiation emitted by a diffuse surface may be approximated as follows. HW 2 Q2 (a) What is the

total emissive power? (b) What is the total intensity of the radiation emitted in the normal direction and at an angle of 30° from the normal? (c) Determine the fraction of the emissive power leaving the surface in the directions π/4 ≤ θ ≤ π/2.
Physics
1 answer:
Ronch [10]3 years ago
8 0

Answer:

a)<em> 2000 W/m²  </em><em>; </em>b) 636.94 W/m<em>².sr ; </em><em>c) </em>0.5

Explanation:

a)

The formula for calculation of total emissive power is:

Total emissive power = E = \int\limits^\alpha_0 E'<em>λdλ</em>

<em>                                    </em>= \int\limits^a_0(0)d<em>λ + </em>\int\limits^b_a(100)d<em>λ + </em>\int\limits^c_b(200)d<em>λ + </em>\int\limits^d_c(100)d<em>λ </em>\int\limits^e_d(0)d<em>λ</em>

<em>where a = 5; b = 10; c = 15; d = 20; e = 25</em>

<em>                                    = 0 +100(10-5) + 200(15-10) +100(20-15) + 0</em>

<em>                                    = 2000 W/m²</em>

b)

The formula for total intensity of radiation is:

I_{e} = E/π = 200/3.14 = 636.94 W/m<em>².sr  </em>

<em>c)</em>

Fo submissive power leaving the surface in range π/4 ≤θ≤π/2

[E(π/4 ≤θ≤π/2)]/E = \int\limits^f_0\int\limits^g_0\int\limits^i_h Icosθsinθ dθdΦdλ

where f = infinity, g=2π, h=π/4, i=π/2

By simplifying, we get

                           = (-1/2)[cos(2π/2)-cos(2π/2)]

                           = -0.5(-1-0)

                           =0.5

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