I am trying to start a discussion on the Effects of EM on matter (biological, electronic and other matter). I am trying to understand the relationship between quantities Electromagnetic (EM) and effects on matter. In particular many types of EM used for medical purposes and can reach certain parts of the body with out effect others (Cutting,heating,imaging,resonating,flexing...) in (MRI,CAT,Laser Surgery...). I am trying to understand how this is possible and the quantiles involved. The formula E=hf is used to define absorption in my sources, but they talk about energy needed to bring to the atom to the next energy level? -So usably given a mix (wave length, frequency) and (Watts or joules). From this I am attempting to find what matter will absorption the frequency? Especially when going through matter of different densities. -And what quantities (Volts, Charge,Pressure,Force,Energy,Temperature) that matter will be induced with? -Any known biological effects caused by Absorptions?