Question

Demonstrate how the spectral emissive power inside a blackbody cavity changes with respect to the
following parameters:
a) Temperature and wavelength, hence, find E?(?, T), by:
(i) Creating a table with the (?, T) values as follows:
1. Wavelengths, ?, from 0.1 ?m to 100 ?m, on the first (left-most) column. Use increments
of:
? 0.1 ?m from 0.1 ?m to 1.0 ?m;
? 0.5 ?m from 1.0 ?m to 10 ?m;
? 1.0 ?m from 10 ?m to 100 ?m;
2. Temperatures, T, values of: 273.15 K; 773.15 K; 1273.15 K; 1773.15 K; 2273.15 K; 5000
K; and, 10000 K.
3. Calculate E?(?, T) using units of W/m2·?m and assume the constants C1 = 374210000
and C2 = 14388.
Set up your table with each separate column corresponding to each given value of T.
Ensure that you clearly label each column in your table and include the relevant units.
[Hint: There should be seven separate columns in your table for the E?(?, T) calculations
and eight columns in your table altogether with the inclusion of the left-most column
consisting of the ? values.
The recommendation is that you fill in each separate column in your table using a
different background colour in order to facilitate the examination of the different T
calculations and to assist in identifying the corresponding plots.]
4. Clearly demarcate the visible region in your table. You may do this by selecting a
different coloured font for the values of ? (and the corresponding E? values) that fall
within this region.
(ii) Plot the calculated values of E?(?, T) ensuring that you set out each plot as follows:
1. Display the calculated E?(?, T) values on the vertical axis.
2. Display the wavelengths on the horizontal axis. Select the logarithmic scale, to base 10,
to display your values on this axis.
3. Clearly demarcate the visible region in each plot.
4. Include a title in each plot, clearly identifying the relevant value of T and ensure that you
label both axes (including units).
[Hint: The recommendation is that you fill in the background of each plot in the same
colour as the corresponding column in your table in order to facilitate the analyses of
the different T calculations.]

Answer 1