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3 years ago

If a wave hits a smooth surface at an angle of incidence of 40 degrees, the angle of reflection is

2 answers:

5 0

As the surface given is a smooth surface, we can use specular reflection. According to the law of specular reflection, the angle of incidence equals the angle of reflection, so it will also be 40°. Answer is A.

sashaice [31]3 years ago

5 0

If a wave hits a smooth surface at an angle of incidence of 40 degrees, the angle of reflection is 40 degrees.

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3 years ago

Two parallel disks of diameter D 5 0.6 m separated by L 5 0.4 m are located directly on top of each other. Both disks are black

oksian1 [2.3K]

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$Q = FA\sigma\Delta T^4$

Where,

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A = Cross sectional Area

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D = 0.6m

$L = 0.4m\\T_1 = 450K\\T_2 = 450K\\T_3 = 300K$

The view factor between two coaxial parallel disks would be

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Then the view factor between base to top surface of the cylinder becomes $F_{12} = 0.26$ . From the summation rule

$F_{13} = 1-0.26$

$F_{13} = 0.74$

Then the net rate of radiation heat transfer from the disks to the environment is calculated as

$\dot{Q_3} = \dot{Q_{13}}+\dot{Q_{23}}$

$\dot{Q_3} = 2\dot{Q_{13}}$

$\dot{Q_3} = 2F_{13}A_1 \sigma (T_1^4-T_3^4)$

$\dot{Q_3} = 2(0.74)(\pi*0.3^2)(5.67*10^{-8})(450^4-300^4)$

$\dot{Q_3} = 780.76W$

Therefore the rate heat radiation is 780.76W

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