Electricity hurts, but differently when you add more hertz:
The hurting from electricity depends on a few factors, like body resistance (from skin thickness, tissue type, humidity), electricity level, duration and frequency. Less resistance, higher level and duration all hurt more. But how does frequency effect the hurtage (I claim that a word! If you use it enough, MS Word won’t show those red wiggly lines underneath it).
I had some past experience where DC hurt less than AC due to body capacitance and super high frequency wouldn’t hurt like low frequency. But here I investigated in more details by applying 4Vrms (AC) voltage across my tong at different frequencies.
One important thing I noticed was that around 22Hz, the lights around me started to flicker. This was an indication that the voltage on my tong was effecting my vision, which would mean the electricity was actually spreading further in my head than I thought. So don’t try this kids! It would cause brain damage… ah, for some reason I can’t stop drooling…
I assume that frequency was likely vibrating my eye muscles causing my eyes to shake mildly, which would make me see lights flickering. Otherwise it should be electricity messing with my optic nerves, but I think the first reason is more likely.
In any case, the experiment is done and the following plot was obtained, by measuring my hand location in screen and plot it against the frequency at that hand height.
The discomfort starts at DC (0 Hz) and starts rising, kind of linearly to around 2kHz, and from there drops to zero around 20kHz.
The muscles contract by electricity. At small frequencies they move muscles back and forth, which feels like twitching. You have the same feeling when your eye lids twitch from being tired. This vibration rises at 10 to 100Hz when you feel like you are being shocked, and feel that shocking buzz in your body. That buzz comes from frequency. But above 100Hz your nerves fail to pick up the frequency (they can’t response that fast) and also your muscles won’t be able to keep up with the vibration speed. And so you feel like a DC cramp in your muscles.The pain is increasing as the frequency rises. I can assume this is because of the body capacitance, which at higher frequency causes more current to pass through body and so hurts more.
Above 2kHz the pain starts to reduce. That could be for a few reasons:
- Human body capacitance drops in value
- Human body inductance increases allowing less current
- Current flows more and more at the surface due to Skin Effect
- Nerves and muscles stop responding to high frequency
So there you have it. I don’t know if this plot has any use. But I leave it to the crowd and maybe someone can make a brake-through in science based on this! If you do, I want my name in the credits!