Your point that impedance at DC and 60Hz is the same may be valid, I couldn't find a proper reference in the few minutes I had available (the Google Books link doesn't work anymore, and the other links didn't mention impedance), but I don't see how your argument supports this. The ideal capacitor has an infinite DC resistance, but depending on capacitance, may have a low reactive impedance. PTFE is a pretty poor conductor, but that doesn't mean that it will dominate the impedance in a PTFE capacitor with an AC signal applied.
Also, the human (dry) skin is a pretty poor conductor, the rest of the body is not as far as I know, and is often considered a good conductor compared to the skin in models of the human body.
I wasn't intending to back up my argument regarding impedance of the human body, just reinforcing what I was saying about the effects of AC vs DC current on the human body being the reason why power frequency AC is more dangerous than DC.
You're right about the impedance of dry skin increasing the reactive component, but if the skin is dry not much current will flow at 50/60Hz because the capacitance will be really low, probably under 100pF. I don't have any information on the permittivity of human skin but I doubt it's high enough to make the capacitance high enough to allow a significant current to flow, if it was it would be used to make capacitors
. At higher frequencies, it's true a significant current can flow due to capacitive coupling but at those frequencies the nerves won't be sensitive to shock so it's low risk. Besides, at low frequencies the insulating properties of the skin have to be compromised anyway to allow a harmful current to flow and damp or carbonised skin will have very poor dielectric properties.
I don't follow this argument either. A microwave oven is about absorption of an electrical field, it's not the induced currents that are dangerous, but the energy (heat). With RF burns, the opposite is the case: the heat is generated by the current, since the body doesn't absorb most of the RF spectrum very well.
You're right there to but if the skin depth of flesh was very shallow the radiation wouldn't penetrate the surface so it would work like a grill.
Ehhhhh, I can't disagree with this statement but the physicist in me is not sure the microwave oven analogy is a good one. Yes, the skin depth is deeper on a more resistive element but in some cases when the magnetic permeability of something is high enough than the skin depth is shallow. Consider iron vs. copper in this case. Iron is more resistive than copper but is a terrible high frequency conductor because of its magnetic properties. The higher the permeability of something the longer it takes the magnetic field from the current to penetrate the material. This limits the current flow to the 'skin' of the conductor.
Human flesh has a low permeability so I don't see what your point is there.
A convential microwave oven heats materials by producing microwaves at frequencies that cause molecular bond structures to harmonically resonate with the oscillating electric field component of the microwaves. This frequency is usually optimized around the OH in H20 since water is present in all foods. A good conducting material will heat or cause sparks because the electrons in the material are easily influenced by the field and allowed to move inside the conductor to oppose the influence of the e-field (more so, no electric field can exist in a conductor which gives rise to some complicated boundary conditions in the case of EM theory which I dont know how to describe without differential equations).
Yes, microwave energy does not penetrate a good conductor and yes it penetrates a poor conductor more thoroughly but the governing phenomenon is different than what gives rise to the skin effect. I don't know if any of that even makes sense. I have already rambled a lot on this thread.
That's another myth, the frequency of microwave radiation has nothing to do with the resonance of water and everything to do with the skin depth and dimensions of a microwave oven. Liquid water has no strong resonant peaks because any resonance is damped by the hydrogen bonds fixing each molecule to its neighbour. Only gaseous water has strong resonant modes because the molecules are free enough to move and the 2.45GHz used in a microwave oven is an order of a magnitude too low to excite any resonance.
http://amasci.com/weird/microwave/voltage3.htmlhttp://www.zyra.org.uk/microw.htm