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(Voltage / Current from Van De Graff Generator) Vs (Voltage / Current from AC Wall Sockets at Homes)

FreshmanNewbie

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The Van De Graff Generator can generator voltages in the kV and MV range.

I have read that if I touch the Van De Graff Generator producing, say 50kV, on one hand (myself being insulated from ground by plastic stool) and the other hand to the grounding rod, I don't get shocked because the current passing through me is less

At the same time, if I take 2 wires from the Live and Neutral from the AC Wall Sockets in home which is 120V or 220 depending on where you are from, and take the Live wire on one hand and take the neutral wire on the other hand (myself being insulated with the same stool), I might get fried. Because even though it has low voltage, it delivers high current

My questions :

  1. Which factor determines the current flow through the human body incase of the Van De Graff generator and the AC Wall Socket?
  2. Why is the current less in the generator case and why is it high in the AC Wall Socket case? Doesn't high voltage means high current? And Low voltage means low current? What am I missing here? Is the missing thing - the internal resistance?
Please help to clear this doubt.
 

betwixt

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1. the two factors are your body resistance and the current compliance of the source.
2. the Van De Graff generator only produces a high voltage UNTIL to you touch it. As soon as current flows through your body the voltage drops to almost zero. The wall socket is capable of sustaining its voltage while current is drawn from it so the 120/220V is still present while you are being fried.

Brian.
 

KlausST

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Hi,

these are different situations:
Any current needs a loop to flow.

With your Van De Graff experiment the stool opens the loop, thus no current flow.

With the mains experiment you close the loop with live and neutral.
To make it comparable to the other experiment, just touch one wire (live or neutral) while beeing insulated on the stool. --> no current.

Klaus
 

Audioguru

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In the winter when humidity is low here, I can shuffle my slippers on the rug and develop tens of thousands of volts of static electricity. The voltage is on me and I can carry it. When I touch something that is grounded then a spark jumps from my finger to ground. It prickles a little for a moment. I do not get fried because the current is almost nothing.
 
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