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What is a capacitor and how it works

 What is a capacitor?

What is capacitor?

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In this article, we will explore what a capacitor is, how it works, and what is its application. The invention of the capacitor brought an evolution in the field of science. A capacitor is an electronic device that stores energy. It is generally a system of two conductors separated by an insulator, which can be paper, plastic, or some form of liquid. Capacitors are used in fan motors, laptops, and various electrical devices. They have the capacity to store energy in the form of charge. There are different types of capacitors present in different sizes and shapes. 

How capacitor works?

How capacitor works?


Capacitors work by having two conductors separated by an insulator. This insulator blocks the flow of charges, causing charges to accumulate on the plates of the conductor when voltage is applied. This stored charge can flow in the circuit, providing electric current even in the absence of any external power source. 

Have have you ever noticed the phenomena of lightning in the clouds. One plate is cloud and other is the ground. Dielectric present between them is the air. Lightning is the result of the releasing of that charge.

The larger the size of the capacitor, the more charge it can hold. You can see the working of a capacitor by taking a battery, a bulb and a capacitor. Connect battery and capacitor with wire. Capacitor will get charged then remove the battery and connect with the bulb. What you will notice is that the bulb will be progressively dimmer and at the end bulb will be finally off due to the discharging of the capacitor,, when the capacitor reaches its capacity

What is capacitance?

Capacitance is the measurement of a capacitor's capacity, measured in farads. One farad capacitor can store a charge of 1 coulomb at one volt potential. However, a one farad capacitor is impossible to have in reality due to practical limitations in size.

Capacitance's formula

In capacitor charge,Q is directly proportional to voltage,V

On introducing a constant,C

Q = C V

Here C is called the capacitance of the capacitor.

We know, 

V= kQ/r

Then C= Q/KQ/r = k/r

This proves that capacitance depends on geometry.

Now suppose we have a capacitor of 1 farad,

Then using above formula

1 = k/r

1= 9×10^9/r

Then r = 9×10^9 metre

This length is too much and couldn't be possible in real to have a device with this distance.

The capacitance of a capacitor depends on its shape, size, and the separation of the two conductors. 


Application of capacitor 

  • Capacitors find application in various  that require a supply of immense power. 
  • They are used in motors to provide initial torque to fans.
  •  For lightning purposes in flash and HID lamps.
  •  Capacitor are used in electronic devices such as computers and televisions for signal coupling and voltage regulation.

History of capacitor 

 German scientist named Ewaid Georg invented the capacitor at first. Later Peter  van musschenbroek, a Dutch professor came up with a device which was credited as the first capacitor. This capacitor was in the form of Leyden jar. It was a simple device consisted of a glass jar half filled with water lined with metal inside and outside. The glass acted as dielectric then the charge would given through a metal wire through a cork from the top of the jar. Jar would have  equal and opposite charges until they were connected with the wire producing a shock.


Capacitor's evolution 

The development of capacitors has brought advancements in the field of electrical science, playing a fundamental role in most electrical circuits and devices, and contributing to innovations in power supply. Many scientific instruments are possible due to the invention of capacitor. The capacitor makes the electronic devices efficient, faster and smaller.

How to increase the capacitance of a capacitor 

As we have already discussed that the capacitance of a capacitor depends on the geometry of the capacitor. The larger the size of the capacitor the larger the capacitance of a capacitor.
Four parallel plate capacitor value of C obtained is 
 C=ε0Ad
In most of the cases we are required to have capacitor of large capacitance of small sizes. In this case capacitance can be increased   by increasing the value of permittivity.

Combination of capacitor 

We can arrange the capacitors in two way that is in series and in parallel. The effective capacitance in series is the
1/C = 1/C1 + 1/C2 + 1/C3 and so on.
The effective capacitance in parallel combination is
C = C1+ C2+ C3 and so on.
By arranging the capacitor in combination of series and parallel we can get effective capacitance of our preference.

Capacitor project 

You can try making your own capacitor for learning purposes.

 Materials you need

  • aluminium foil
  •  plastic for insulation
  •   LED bulb for testing

 Instructions

  •  cut to rectangular pieces of aluminium foil
  •  cut a rectangular piece of plastic for insulation 
  • place the sheet of plastic on the aluminium foil
  •  place the piece of aluminium foil above the sheet of plastic
  • Glue them 

you can test this using a battery LED bulb and wire. Connect the capacitor with battery and the bulb with wire. Remove the battery and observe the discharging of the capacitor.


I hope this article gave you insight on what is capacitor and how it works. If you like it check out more on my site.


References:

https://www.electronics-tutorials.ws/capacitor/cap_1.html

https://www.britannica.com/technology/capacitor

https://en.m.wikipedia.org/wiki/Capacitor

https://www.electronics-tutorials.ws/capacitor/cap_1.html



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