20 Physics -- Capacitor

Why the capacitor stores energy but not charge??

1 Answers

First of all, let's know what really storing anything means. To store something implies there should be presence of some extra amount of it in them. Like same storage of energy or charge in any system implies the net charge or energy in the system is not equal to zero.

Now let's consider a parallel plate capacitor in which the plate connected to the positive terminal of a battery gets positive charge and induces same amount of negative charge on the another plate. So the total net charge becomes zero and hence the capacitor does not store charge and hence its plates only do the separation of charge.

Now let's talk about energy. As there is positive charge on the first plate so it will produce field lines that will create an electric field between the both plates and that cause storage of energy. When we connect the plates generate work and this phenomenon become possible only because the capacitor has stored energy.

So, in the nutshell as the capacitor has net charge zero it doesn't store any kind of charge on it but meanwhile whenever charges of opposite polarity are separated then electrical energy is stored within the capacitor by the same charge present within it. So a capacitor stores energy but not charge.

However, it does not implies that the capacitor does not have any charges, it has a net charge of zero.

Batteries are always labeled with their emf, would it also be appropriate to put a label on batteries stating how much current they provide? Why or why not?

Ans: No, a battery does not always produce the same current, no matter what circuit it’s used in. The current in any electric circuit consisting of a cell of emf E and internal resistance r and an external resistance R is given by

I = E/(R + r)

This equation shows that the current that asourceof emf produces in a given circuit depends on the external resistance R as well as the internal resistance r of the cell. The greater the resistance, the less current thesourcewill produce. So, however, a...

Find the equivalent capacitance of five capacitor networks shown below.

Prove that :Electric field intensity(E)= potential difference (V)/distance between two plates(d)i.e. E=V/d

V=W/q

V=Fd/q

V=F/q*d

V=E.d [E=F/q]

E=V/d

Define dielectric. A dielectric is present in between two plates of a capacitor.

Is it suitable to use capacitor of capacitance 1 Farad in our house? Why? Why not?

Explain the difference between polar and non-polar dielectrics with one example of each .

Polar Dielectric:

1. Contains polar molecules that have permanent electric dipole moments.

2. When an electric field is applied, the polar molecules align themselves with the field.

3. Examples: Water (H2O), ammonia (NH3), and hydrogen fluoride (HF).

Non-Polar Dielectric:

1. Consists of non-polar molecules that lack permanent electric dipole moments.

2. They do not align with an applied electric field.

3. Examples: Carbon dioxide (CO2), methane (CH4), and oxygen (O2).

The key difference is that polar...

A capacitor has a vacuum in the space between the conductor plates. If you double the charge on each conductor, what happens to the capacitance?

When charge is given to a capacitor thepotential difference across its plates rises. Asthe more and more charge is given, itspotential increases accordingly. If a charge Qis given to the capacitor so that its potentialrises through V, then it has been found thatcharge Q stored in it is directly proportional topotential difference V across the plates of thecapacitor. So,

Q V

Q = CV

where C is a proportionality constant, calledthe capacitance of the capacitor. Its valuedepends upon the shape and...

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