The discussion revolves around the absorption and reflection of different wavelengths of radiation by various objects, particularly focusing on humans and their interaction with visible light and infrared radiation. Participants explore concepts related to thermal radiation, temperature effects, and the nature of light-matter interactions.
Participants express varying views on the effects of visible light on human bodies and the nature of light-matter interactions, indicating that multiple competing perspectives remain without a clear consensus.
Some participants reference Wien's law and the concept of ionization without fully resolving the implications or definitions involved, leaving certain assumptions and dependencies unaddressed.
LogicalAcid said:For example, humans emit primarily in the Infrared part of the spectrum, so then why is it that when visible light falls upon us, it is not converted to heat immediately?
sophiecentaur said:The peak in the spectrum of radiated em energy depends upon the temperature of the surface of the object. For humans, at normal body temperature, the peak is in the IR region. If visible light falls on a human then his / her temperature may rise a tiny bit due to the absorbed energy. That will alter the peak in the radiated spectrum but, of course, humans regulate their (core) temperature so there will be compensating mechanisms to keep the surface temperature from getting too high. For an inanimate object, the temperature that it will finally reach will be higher, according to just how much energy falls on it and also on the temperature of the source of the radiation.
LogicalAcid said:This is wiens law, but I still don't understand, if the visible radiation around us can ionise atoms, why aren't we glowing masses of plasma?