Choose one of the given materials to surface a building and justify your reasoni

Question

Choose one of the given materials to surface a building and justify your reasoning:

Material 1: transmits 60% of the incident radiation betweeen 300nm - 600nm and 20% of the energy between 600nm - 4,000nm.

Material 2: transmits 40%of the incident energy between 300nm - 2,000nm and 30% of the energy between 2,000nm-30,000nm.

Table 6-1 Blackbody Radiation Functions ?? (mKx 10*)* 6.2 (mKx 103)' 0.341796x 10-26 0.186468x10-11 0.929299 x 107 0.164351x 104 0.320780 × 10-3 0.213431x 10-2 0,779084x 10-2 0.197204x 10-1 0.393449 × 10-1 0.667347 × 10-1 0.100897 0.140268 0.183135 0.227908 0.273252 0.318124 0.361760 0.403633 0.443411 0.480907 0.516046 0.548830 0.579316 0.607597 0.633786 0.658011 0.680402 0.701090 0.720203 0.737864 0.754187 0.769282 0.783248 0.796180 0.808160 0.819270 0.829580 0.839157 0.848060 0.856344 0.874666 0.890090 0.903147 0.914263 0.923775 0.931956 0.939027 0.945167 0.955210 0.962970 0.969056 0.973890 0.980939 0.985683 0.992299 0.995427 0.998057 0.999045 0.999807 1.000000 0.2 0.4 0.6 7.0 7.2 7.4 7.6 7.8 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12 13 14 15 16 18 20 25 30 40 50 75 100 1.4 1.8 2.0 2.2 2.8 3.0 3.2 4.2 5.2 5.6 6.0

Explanation / Answer

2.06 eV = 2.06 x1.6 x10^ -19 = 3.296 x 10^ -19 J
KE = hc/wavelength - work function
a) for wavelength 800 nm
0.5 x 9.1 x10^ -31 (v^2) = 6.625 x10^ -34 x 3 x10^ 8 /800 x10^ -9 - 3.296 x 10^ -19
v = -ve which means electron cannot be ejecte using 800 nm wavelegth
b) for 600 nm
0.5 x9.1 x10^ -31(v^2) = 6.625 x10^ -34 x3 x10^ 8/600 x10^ -9 - 3.296 x10^ -19
v = 6.022 x 10^ 4 m/s
c) for 300 nm
0.5 x9.1 x10^ -31 (v^2) = 6.625 x10^ -34 x3 x10^ 8/300 x10^ -9 - 3.296 x10^ -19
v = 8.55 x10^ 5 m/s

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