# Charge on the plate of the capacitor

I was reading parallel plate capacitors in my book today and there I saw that the battery provides +Q charge to positive plate and -Q charge to negative plate? But we know that only electrons can flow so the battery should provide only -Q charge right?

Is it that, the electrons flow from the negative terminal of the battery to the negative plate and since the conductor is seperated by a dielectric medium, here (air) the negative charge will pile up at the negative plate, but since the seperation is less this will induce a positive charge on the other plate of the capacitor and since positive charge can't flow so it will stay there only. Also, the negative charge is provided by this positive plate only, which is then transferred by the battery to the opposite side of the capacitor or the negative plate? Is this explanation correct?

Also, My teacher said that the battery provides energy to the charges but my book says that the battery provides the charges, I'm totally confused.

Please help me.

## 1 Answer

You have got the right idea. When a circuit consisting of a battery and capacitor is switched on, the electrons from the negative terminal start accumulating on the capacitor plate. The negative capacitor plate induces an equal and opposite charge on the other capacitor plate. Together, an electric field is created and there is a new potential difference in between the plates. This potential difference serves to counter the emf provided by the battery.

The electrons from the positive plate go into the positive terminal and the battery is slowly consumed. This occurs until the enduced potential difference perfectly balances the battery. When this happens, we say that the capacitor has become charged and $$\frac12CV^2$$ worth of energy has been used up by the battery in doing so. The battery provides the potential difference which allows for the flow of charge. Both the textbook and your teacher are correct.