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By Coulomb's law, say if we have 2 point particles each having a charge of +1C then by the formula, F = k/(d)^2

if we need to make the distance between them zero, clearly y the formula, we need to have an infinite amount of force.

However, in a real life scenario, we see that if we rub two balloons with our head, they acquire the same charge. However, it is still possible to make them touch.

Is this because the two balloons are not point objects? OR is the definition d=0 actually mean "to occupy the same space".

for d to be 0, do the objects only need to touch or do their centers need to be together?

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  • $\begingroup$ You might wanna see this:physics.stackexchange.com/questions/23797/… very simply, two objects can never touch, only come pretty close apart. $\endgroup$ – udiboy1209 Aug 11 '13 at 16:10
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    $\begingroup$ Note that Coulomb's law applies to point charges. Also, it happens to work for uniform perfect spheres of charge (why? good exercise to work it out). In that case $d$ is the distance between the centres, not the surfaces. $\endgroup$ – Michael Brown Aug 11 '13 at 16:33
  • $\begingroup$ Please read my answer to a similar question physics.stackexchange.com/questions/72927/… . When infinities appear of any sort in extrapolation of theories, it means a new theoretical framework is necessary, usually provided by quantum mechanics. Electrons are point charges, but the heisenberg uncertainty principle ( look it up in wiki) eliminates infinities. $\endgroup$ – anna v Aug 13 '13 at 19:54
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No you can't bring charges in contact with each other even if they are oppositly charged because when they come too close to each other the nuclear force of repulsion would overcome the force of attraction due to the charges and their other factors too the link in one of the above comment by udiboy has the better explanation.
and now As much I know the phenomenon that happens with balloon is yes because they are not point charges when you bring two balloons closer having same charges the charge on the side of the balloon's changes due to conduction and the two adjacent side's acquire opposite charges as in the image

enter image description here

hope you understood

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  • $\begingroup$ +1. Also include explanation point charges never touching? Just makes the answer feel more complete :) $\endgroup$ – sihrc Aug 13 '13 at 14:49
  • $\begingroup$ This is not quite correct. The charges inside the balloons will redistribute, but they will leave the extremes positively charged and the middle sections neutral: not $+,-,+,-$ but $+$, neutral, neutral, $+$. $\endgroup$ – Emilio Pisanty Aug 13 '13 at 16:11
  • $\begingroup$ haha man this not an HD image so just chill $\endgroup$ – Dimensionless Aug 13 '13 at 16:13

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