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Suppose I have a charged capacitor and I only touch one of the plates or leads.

Will current start flowing through my body?

I think yes, because there is an electric field between one plate and Earth/ground.

Will the Coulomb force push charge through my body as soon as I touch the lead?

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    \$\begingroup\$ No, you will only charge/discharge your self capacitance of ~100pF. The charge imbalance on the cap will remain. \$\endgroup\$
    – tobalt
    Commented Aug 7, 2021 at 17:30
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    \$\begingroup\$ Yes current will flow. You are correct. But it would be a fee picoamps for a few picoseconds...not enough to electrocute you. \$\endgroup\$
    – Kyle B
    Commented Aug 7, 2021 at 17:41
  • \$\begingroup\$ thanks, how can i mark my question as answered? \$\endgroup\$
    – user2276094
    Commented Aug 7, 2021 at 17:58
  • \$\begingroup\$ I cannot miss this one. :) Oh Yah! It is one way to kill someone. We played tricks with charged capacitors at college. And, it sure makes someone mad every time. You are brave enough to test it to yourself. \$\endgroup\$
    – jay
    Commented Aug 7, 2021 at 18:47
  • \$\begingroup\$ A second thought, you are right, I am less right, but I do no want to touch a charged cap. \$\endgroup\$
    – jay
    Commented Aug 7, 2021 at 19:13

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This is highly specific to circumstances, voltages and capacitances involved. A definitive answer without that information would be irresponsible.

If the question is "can a capacitor discharge in to me if I only touch one lead" then the answer is the same. It depends on the circumstances, voltages and capacitances involved.

Most of the time a charged capacitor is not in complete isolation, one side could even be earthed or connected to the chassis so a path could be found, especially at high voltages, even through things that are not normally considered to be conductive such as air. I'm not saying this is a common danger especially with lower voltages. Only that a charged capacitor should be treated with respect even if a current return path is not immediately obvious. I would not want a reader to come to the conclusion that touching a single pin of the capacitor is safe to do in all circumstances.

Lower voltages and capacity's are generally safe to work with but depending on the circumstances could still pose some risk and should be treated with respect.

This video demonstrates some of the risk at the extreme end. Big Capacitor Safety

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    \$\begingroup\$ Then show a case where it would be dangerous! Even if you consider the biggest meanest conceivable capacitor. charge it, then first touch one led, let go and touch the other led, nothing bad would happen, because you will charge only your self capacitance (which can be an obvious zap in the finger but not dangerous). In the video obviously they touch both leads, which is dangerous. \$\endgroup\$
    – tobalt
    Commented Aug 7, 2021 at 18:37
  • \$\begingroup\$ Most of the time a charged capacitor is not in complete isolation, one side could even be earthed so a path could be found at a high enough voltage. I'm not saying this is a common danger especially with lower voltages. Only that a charged capacitor should be treated with respect even if a current return path is not immediately obvious. I did not want a reader to come to the conclusion that touching at single pin of a capacitor is safe to do in all circumstances. \$\endgroup\$
    – Kezat
    Commented Aug 7, 2021 at 19:03
  • \$\begingroup\$ so when i stick the lead into earth. what potential will earth have? i mean shouldnt electrons from earth be drawn towards the positive capacitor plate until there is an equilibirum of forces? so then earth will have positive potential at some point? \$\endgroup\$
    – user2276094
    Commented Aug 7, 2021 at 19:05
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    \$\begingroup\$ You are right, if the other terminal has some path to ground, which at very HV can be even through air. So it would be good to include this in your answer.. I also generally agree about charged caps and respect. I double check my action in a similar way as with mains voltage. :-) \$\endgroup\$
    – tobalt
    Commented Aug 7, 2021 at 19:08
  • \$\begingroup\$ I'm realizing that the original question was probably more about the technical details and not directly about safety. Should a edit to the title be done to better reflect that if that's the case? @user2276094 \$\endgroup\$
    – Kezat
    Commented Aug 7, 2021 at 19:35

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