2.
(a)
An object which can be modelled as a blackbody is heated to different
temperatures, represented by the four lines and their spectra are
recorded in Figure 2.
Intensity
B
A
C
10-
8-
6-
4-
2-
0
0
1.0
2.0
3.0
Wavelength ? (?m)
Figure 2
Based on Figure 2,
(i)
interpret sections A, B, and C as visible, ultraviolet and infrared
wavelengths, respectively.
(ii)
explain why metal turns from red to white and gets brighter as it
gets hotter.
(30/100)
(b) Betelgeuse is our nearest red giant star. It has a power output of
$4.49 \times 10^{31}$ W and emits radiation with a peak wavelength of 850 nm.
Determine the ratio of the radius of Betelgeuse, $r_b$ to the radius of the
Sun, $r_s$.
(30/100)
