What is Capacitor?

A capacitor is originally known as a condenser, is a passive two-terminal electrical component used to store energy electrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors are plates separated by a dielectric called insulator. The conductors can be thin films of metal, aluminum foil or disks, etc. The 'nonconducting' dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, paper, mica, etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, a capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

When there is a potential difference across the conductors examples are when a capacitor is attached across a battery, an electric field develops across the dielectric, causing positive charge (+Q) to collect on one plate and negative charge (-Q) to collect on the other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if an accelerating or alternating voltage is applied across the leads of the capacitor, a displacement current can flow.

An ideal capacitor is characterized by a single constant value for its capacitance. Capacitance is expressed as the ratio of the electric charge (Q) on each conductor to the potential difference (V) between them. The SI unit of capacitance is the farad (F), which is equal to one coulomb per volt (1 C/V). Typical capacitance values range from about 1 pF (10−12 F) to about 1 mF (10−3 F).

The capacitance is greater when there is a narrower separation between conductors and when the conductors have a larger surface area. In practice, the dielectric between the plates passes a small amount of leakage current and also has an electric field strength limit, known as the breakdown voltage. The conductors and leads introduce an undesired inductance and resistance.

Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies. In resonant circuits they tune radios to particular frequencies. In electric power transmission systems they stabilize voltage and power flow.

does the distance between the plates affects the capacitance?

ivylopez wrote:does the distance between the plates affects the capacitance?

yes, you can reduce the capacitance by increasing the distance.

Why do real capacitors have polarity marked on them.They are just plates we can connect them in either way right?

lanz wrote:Why do real capacitors have polarity marked on them.They  are just plates we can connect them in either way right?

Not all capacitors have polarity. Only electrolytic capacitors are the ones that have an insulator (dielectric) created by a chemical reaction. If you reverse polarize them, you reverse the chemical reaction creating a short circuit.

capacitors will never be the next energy solution

lanz wrote:capacitors will never be the next energy solution

okay

What is a capacitor used for?

marky wrote:What is a capacitor used for?

Every 'bit' of computer memory, (1 and 0) uses a very small capacitor, so a common smartphone contains billions of capacitors. Timing circuits use capacitors, as well as circuits which change alternating current to direction current. There are many other uses as well.

WHAT HAPPENS IF WE KEEP ON CHARGING THE CAPACITOR?

SarahMae wrote:WHAT HAPPENS IF WE KEEP ON CHARGING THE CAPACITOR?

Capacitor will keep charging, but with a decreasing current.

Why the need for the capacitor? why not just attach the battery for the power source?

SarahMae wrote:Why the need for the capacitor? why not just attach the battery for the power source?

Capacitors are used for much more than power sources. They are also used to create timing circuits, converting AC to DC, filtering out DC, noise filtering, memory chips and more.

Just starting out in electronics so reading lots of forums and blogs online, this is the best capacitor thread I have seen so far.

Now i have a better idea of the working mechanism of a capacitor.

Why is a capacitor used in a fan?

Nico wrote:Why is a capacitor used in a fan?

Because once the fan starts rotating, due to its inherent nature, a permanent forward field is always available. So the auxiliary winding along with the capacitor can now be removed from the circuit.

How does a capacitor store energy?

Nico wrote:How does a capacitor store energy?

Capacitor is consist of two conductors ( plates ) which are separated by insulator ( dielectric). A capacitor stores energy when it is connected to a voltage source such as a battery or any other source, current flows until the capacitor becomes charged to the same voltage as the source connected to it.

If capacitance can hold charge what is battery?

marky wrote:If capacitance can hold charge what is battery?

It basically does the same thing but a battery releases it charge over a longer time.

mastercoder wrote:

marky wrote:If capacitance can hold charge what is battery?

It basically does the same thing but a battery releases it charge over a longer time.

A battery produces electric charges for current flow through chemical reactions. A capacitor does not operate by way of chemical reactions.

Admin wrote:

mastercoder wrote:

marky wrote:If capacitance can hold charge what is battery?

It basically does the same thing but a battery releases it charge over a longer time.

A battery produces electric charges for current flow through chemical reactions.  A capacitor does not operate by way of chemical reactions.

A battery provides voltage as well as charge but a capacitor only provides charge. Tell if Im wrong

ivylopez wrote:

Admin wrote:

mastercoder wrote:

marky wrote:If capacitance can hold charge what is battery?

It basically does the same thing but a battery releases it charge over a longer time.

A battery produces electric charges for current flow through chemical reactions.  A capacitor does not operate by way of chemical reactions.

A battery provides voltage as well as charge but a capacitor only provides charge. Tell if Im wrong

A capacitor stores charge but it also produces a voltage across its terminals. From this standpoint, a capacitor "looks like" a little battery. However, it is not a battery, because a battery uses chemical reactions to produce voltage and charge. A capacitor does not use any chemical reactions.

when to use capacitor and why?