Does anybody know how I can calculate if an electromagnetic wave of a certain frequency will be able to pass through a given material (specifically wood)?
Second, I know that fluorescence involves a material that will emit light at a frequency lower than the light that strikes it. Are there any materials that exhibit similar properties when struck by radio waves?
Thanks
The absorbtion spectrum of complex materials is usually found by measuring it. Calculation would only work if the substance was very simple (such as a pure crystal,) and if each equation for each of many different absorbtion/scattering effects were included.
Rule of thumb: if it’s an insulator, then it’s transparent for all EM radiation below the microwave spectrum (and often transparent to microwave too.)
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Second, I know that fluorescence involves a material that will emit light at a frequency lower than the light that strikes it. Are there any materials that exhibit similar properties when struck by radio waves?
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For microwaves, yes, but not for radio waves. In a “Maser” amplifier a molecule “fluoresces” with microwave radiation.
If you’re trying to make a “fluorscope” for radio waves rather than for x-rays, a way to do this is to use a tiny radio receiver to drive an LED, then move the assembly very fast in a spiral motion. This gives a kind of “raster scan.” Wherever the radio waves are intense, the LED lights brightly. There was a book in the 1950s by Bell Labs Scientist Winston Kock called ‘Seeing Sound’ where he made flouroscope scanning devices which displayed patterns of sound waves and patterns of microwave radiation. His devices moved slowly, and he recorded the glowing raster with a long-exposure camera.