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We know that $C=q/U$. We know that the voltage is the potential difference between the plates. If we have a capacitor on which we apply voltage, the one plate charges up and induces the other one with an equal and opposite charge. If we connect one of the plates to ground, will the voltage change ? if so why? If not, why?

By grounding, we give one of the plates an infinite sink/well of charge (meaning by grounding we either let the positively charged plate get it's missing charge, or the excess electrons on the negative plate to go into the ground. Therefore, we change the potential on one of the plates. So the voltage (the potential difference) drops. Am I missing something? Is it right?

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  • $\begingroup$ You have connected one plate to ground, but what have you done to the other plate? $\endgroup$ – Aaron Stevens Oct 18 at 19:32
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You are absolutely right in you understanding that the potential will drop; it will drop to zero.

By convention the earth's electrostatic potential is taken to be zero , so when we ground the plate the, the need to level out the potential difference causes negative charges to flow up to the positively charged plate and vice-versa, since the charges dealt here are very minuscule and the earth is massive in size compared to that of the plates harboring the charges there will not be any change in the potential of the earth.

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