The skin of a person is at about 310 K. Use Wien's constant b = 2.898 × 10⁻³ m K and hc = 1240 eV…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The skin of a person is at about K. Use Wien's constant m K and eV nm. At what wavelength does the skin shine most strongly, and in which band is this? What is the energy of a photon of that wavelength?
Need a reminder? The key ideaShow
Hot bodies follow Wien's law, m K. An X-ray tube at voltage gives a shortest wavelength . A radar echo gives the distance . A microwave oven works at GHz.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The peak wavelength. .
Step 2. The band. It is far above nm, so it is infrared. This is why a thermal camera sees people in the dark.
Step 3. The photon energy. nm, so .
Answer: , in the infrared; eV.
Check. A photon of visible light has eV to eV, much more than this. A body at room temperature gives out no visible light.
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