u/FoolishTook7

(I tried posting this in r/askelectronics and r/ElectricalEngineering. Apparently, this topic isn't relevant to those subreddits. If you decide to remove this post from r/AskPhysics, could you recommend some places that may be interested in answering? This question is a topic brought up by my college physics professor)

A man in a grounded metal suit stands near a tesla coil. The coil is activated, and a bolt of electricity sparks to the man. Does the man in the suit get shocked?

I am pretty sure the answer is no, but I am trying to nail down exactly why.

My first answer is that the suit is a much better conductor than the human body. Current flows in path of least resistance, and will go through the suit, leaving the person un-roasted.

I have a qualm with this explanation. If I understand things correctly, the sparks from the Tesla coil are plasma, and have very low (negative?) resistance. This would mean that even the very low resistance of the suit may be large compared to the whole system, which would mean there is a non-trivial voltage potential across the suit. Since current is flowing, and the suit isn't a perfect conductor, the voltage drop is obviously non-zero.

In order for Hongbin to not be electrocuted, the voltage source must not be an ideal voltage source. Either the resistance between the coil and suit is significantly higher than the suit, or something else inside the coil is regulating the current.

Another explanation I heard is the skin effect in electronics. At high frequencies, current tends to flow on the outside of conductors. Since the human is on the inside of the conductor, dV there would be 0, and the person would be safe. Does this extend to DC voltages? If the arc is DC vs AC, would the occupant be cooked?

I look forward to the discussion. I shall be standing by with popcorn! I may post this to adjacent groups as well.

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u/FoolishTook7 — 10 days ago
▲ 3 r/ElectroBOOM+1 crossposts

I am pretty sure the answer is no, but I am trying to nail down exactly why.

My first answer is that the suit is a much better conductor than the human body. Current flows in path of least resistance, and will go through the suit, leaving the person un-roasted.

I have a qualm with this explanation. If I understand things correctly, the sparks from the Tesla coil are plasma, and have very low (negative?) resistance. This would mean that even the very low resistance of the suit may be large compared to the whole system, which would mean there is a non-trivial voltage potential across the suit. Since current is flowing, and the suit isn't a perfect conductor, the voltage drop is obviously non-zero.

In order for Hongbin to not be electrocuted, the voltage source must not be an ideal voltage source. Either the resistance between the coil and suit is significantly higher than the suit, or something else inside the coil is regulating the current.

Another explanation I heard is the skin effect in electronics. At high frequencies, current tends to flow on the outside of conductors. Since the human is on the inside of the conductor, dV there would be 0, and the person would be safe. Does this extend to DC voltages? If the arc is DC vs AC, would the occupant be cooked?

I look forward to the discussion. I shall be standing by with popcorn! I may post this to adjacent groups as well.

u/FoolishTook7 — 10 days ago