# Hand contact with capacitor negative (excess of electrons) terminal only.

Discussion in 'General Electronics Chat' started by Aspenforest, Jan 29, 2013.

1. ### Aspenforest Thread Starter New Member

Jan 29, 2013
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Thank you for any help you are able to provide.

I myself think that the electrons will flow to the
human body and further drain the battery.

2. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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Describe your reasoning in coming to this conclusion.

3. ### russ_hensel Distinguished Member

Jan 11, 2009
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Why would the body be at a lower potential? And if it is there must be a force.

4. ### Aspenforest Thread Starter New Member

Jan 29, 2013
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I viewed electrons as a fluid. If I push electrons into a capacitor,
they are there under a pressure. Then due to entropy they would
want to naturally flow to a low-pressure area, where there are less electrons.
So the analogy would be a high pressure water container,
from where water would want to escape to the surrounding
medium to balance the pressure difference.

5. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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Where would current the human body picks up originate from?

6. ### #12 Expert

Nov 30, 2010
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You have to think in terms of a circuit loop. The human must have some capacitive connection to the positive terminal, or there is no potential difference. No voltage = no current. Without a loop, the electrons have no incentive to charge the human to 9 volts.

In the most minute terms, everything is capacitively coupled to everything else, but the capacitance level is microscopic. Therein lies the quantity of capacitance, and therefore, the quantity of electrons that will flow. It's probably unmeasurable. However, you might estimate a pico-pico farad of coupling to the positive terminal and calculate a number of electrons.

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7. ### Aspenforest Thread Starter New Member

Jan 29, 2013
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But how do you then explain a Van de Graaff generator with a top negative capacitor sphere, which is charged to a high voltage? When you touch that negative sphere capacitor, your hair will stand out, meaning that electrons are transferred to the human body from the negative terminal. Isn't it the same capacitor system, only with high voltage?

8. ### #12 Expert

Nov 30, 2010
16,703
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How do I compare a hundred thousand volts to 9 volts? I don't.
The principle is still valid, but at a hundred thousand volts, the air becomes a valid conductor and the soles of your shoes become a significant capacitor with respect to the ground you are standing on.