Capacitors(basic idea)

To give you a brief idea about capacitors let's start with selecting two large sheets of metal of the same size and setting them up so they can face each other.Now we have to mount them in such a way so that no electrical conduction path exists between the plates and the plates are fairly close to each other.This arrangement is known as a capacitor.And the metal sheets that I have talked about are the plates.Now, the gap that exists between two plates holds a insulating material which is in this case is air and is also known as the dielectric.A perfect capacitor is one whose dielectric permits no current to flow from one plate to the other.We shall be dealing with perfect capacitors but not leaky capacitors.

Now, let's start with the most important thing on how to charge a capacitor??

As you can see from the figure positive terminal oif the battery is connected to the plate that holds the positive charges(let's say the total charge be Q+),and the negative terminal is connected to the plate that holds the negetive charges.The electrons flow from the negetive terminal of the battery to the plate that holds the negetive charges(negetive charges on this plate is due to the flow of electron from the -ve terminal of the battery) and this in turn induces positive charges on the plate that is exactly parallel to it.Now, a question lingers that why there is positive charges on the plate,this is because due to repulsion electrons are kicked out from the plate .This constitutes a current flow in the circuit.The flow of current shall continue till the potential difference of the plates exactly matches with the emf of the battery.At this point,current ceases to flow.

(this is how a capacitor looks)

• Relation between Q and V:-

It can be experimentally observed that the potential difference is directly proportional to the charge Q.

Now you can write that Q=CV where C is the proportionality constant also known as capacitance.

But you may think why charge on one plate appears in the formula, it should be then 2Q but the fact is it is not.This is because Q is a quantity of electricity that moves through the connecting wires during charging process and not 2Q.