Basic physics courses usually resort to explaining the color of astronomical bodies like stars in terms of their temperature as per Wien’s law of displacement. Looking at the peak of the spectrum for bodies capable of black body radiation may be an error. It would seem more suitable to consider this topic by means of reference to photon statistics
The well-established scientific theory of black body radiation simply must be taught as part of any physics course, even at the most basic level. An understanding of this crucial concept is indispensable in modern physics so it is paramount that it is taught effectively and with as little room for misinterpretation as possible.
The primary area of issue lies in the incorrect application of Wien’s law for objects capable of black body radiation. If the color of a given star could be determined by the position of the peak of the associated Planck curve, then it ought to be the case that the energy level emitted in this color is much higher than that of any other part of the visible spectrum. The problem with this interpretation is that the peak of a star’s Planck curve is practically at a plateau in the visible region of electromagnetic radiation.
Entry level physics lessons tend to treat black body radiation by plotting Planck curves as a function of wavelength. This approach requires that an independent variable is chosen when expressing Wien’s law of displacement and drawing up a Planck curve. Though this method does describe the relevant physics appropriately, another way of doing this plots instead the emitted power per unit area per steradian per frequency interval. This gives a different shape of curve and, as a result, the former and latter approaches produce peaks at different spectral positions.
Another, more practical issue with the use of Wien’s law when discussing the physics of black body radiation is that this law isn’t really used to work out the temperature of a given object emitting thermal energy. One could use Wien’s displacement law for the purpose of estimating the approximate value range within the electromagnetic spectrum in which a given source will most strongly radiate thermal energy. However, this doesn’t narrow down the numbers to a useful and accurate value. Instead, the Planck function must be made to fit the intensity of emission by altering the temperature value in the equation itself.
When teaching this fundamental aspect of physics, especially in the case of first introductions to the topic, it is of utmost importance that the student is not left to make misconceptions and come to inappropriate conclusions. It is far better to explain more advanced concepts in a stepwise fashion than to simplify facts and theories to the point of misinformation. Following this approach, students of physics will sidestep the pitfalls often associated with obtaining a working understanding of this part of physics.
