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If the plates of a parallel plate capacitor attract each other
with some force (equal to charge on the capacitor multiplied by the electric field due to either of the two plates), why don't the plates collide?
- Raviroop Singh (age 17)
Well there is certainly a force on them, as you said, the charge times the electric field.
So, if you turned them loose they would be attracted to each other and eventually collide. In order to prevent this you must have another force to counteract the electrical force. Usually this is in the form of a mechanical structure, as in an air capacitor or, more simply, the material of the dielectric in a typical component of an electronic circuit.
Perhaps you're wondering how those mechanical forces, which are electromagnetic in origin, can hold things apart. The key is quantum mechanics: the electronic states of atoms cannot be squashed without raising their kinetic energies, Mike W.
(published on 02/23/10)
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