What is a Capacitor?It is defined as the ratio of the electric charge Q to the potential difference V.
C = Q / VThe capacitance of a capacitor is measured in units called Farads. A capacitor is said to have one Farad of capacitance only if the capacitor can hold one ampere per second of electrons at one volt at a rate of one coulomb of electrons per second.
The Evolution of CapacitorsThe evolution of capacitors took place in an interesting way. In the 6th century, a Greek scientist ‘Thales of Mileus’ rubbed amber with animal fur. The amber acquired the ability to pick up small bits of material. After several thousands of years have passed (in the 18th century) many changes took place. Von Kleist built the first practical capacitor. He took a medical bottle and filled it partly with water, and then sealed it well with a cork. Later he pushed a nail through the cork into the water. Next, the nail was made to contact with the electrostatic machine, this produced some charge. When Von Kleist was about to touch the nail, he felt the separated charges were able to reunite by flowing through his own body.One of the famous experiments was Leyden Jar. Van Musschenbroek conducted an experiment which can be said as the first capacitor. His experiment was almost similar to Von Kleist’s one; however, he just removed water from the bottle and used metallic foil to wrap both inside and outside of the jar. There was a metal chain which was driven through the cork on the top of the jar. This chain was hooked with something that would produce the charge. The moment charge was delivered, the jar would hold two equal but opposite charges in equilibrium until they were connected with a wire slightly producing either spark or shock.
Symbols Of Different CapacitorsSymbols and Practical Diodes in the Real Time Applications:Capacitor Polarity:Capacitors are measured in the units Farad. Most of the values are in micro Farad. Micro farad is one millionth of a Farad. The PicoFarad is one millionth of a Micro Farad. It is used in radio works. The Pico Farad capacitor size is larger than Micro Farad capacitor. Some of the capacitors are unpolarized like resistors. They can be placed in either way in a circuit. Electrolytic Capacitors have anode and cathode that needs to be placed in a particular direction. Electrolytic capacitors evaporate after 2000 hours at 105 degrees Celsius.
Construction of a CapacitorThe basic model of capacitor is made of two plate metals which are separated by a dielectric material. From this basic concept of construction, capacitors have evolved into many different models of construction..
Construction Of CapacitorReal capacitors are made by taking thin strips of metal foil and dielectric material, and then sandwiching them together.
Capacitor’s Working PrincipleA capacitor in a given supply, current starts flowing into the capacitor. The charge gets struck on both plates as they are separated by a dielectric medium. The electrons that are negatively charged particles are on one of the plates; this makes the plate negatively charged. These large mass of negative charges repel with the like charges on the other plate making it positively charged.Now these negative and positive charges get attracted to each other which create an electric field in between the plates as they are being separated by an insulating material. This phenomenon is just like storing energy in a battery.
Different Types Of CapacitorsElectrolytic CapacitorElectrolytic capacitors are polarized capacitors that have anode and cathode. They use high dielectric constant of the aluminum oxide layer on the plates of the capacitor. This is greater than normal dielectric material.Construction of Electrolytic CapacitorsThe basic capacitor has two plates and one dielectric material. In electrolytic capacitor two plates and foils are slightly different. One of the plates is coated with an oxide layer and the paper is soaked in electrolyte which is placed in between the plates. The foil insulated with oxide layer is the anode. The thickness of the anode oxide is a thin film. The second foil acts as a cathode. This has to be packaged together and form a cylinder. Now, this is placed in an aluminum can to protect it from external force. While manufacturing the electrolytic capacitor, it is necessary to use high purity foil of anode. The general thickness would be 20µm and 50µm.
- Surface Mounted Multilayer Ceramic Capacitors
- Lead Disc Ceramic Capacitor
- Specialist Microwave Bare Leadless Disc Ceramic Capacitor
- To block the flow of DC and permits AC
- To couple the sections
- To send desired signals to any sections
- For phase shifting
- For creating delay time
- In grounding the undesired frequencies
- In motor starter
- To filter the ripples in a rectifier circuit and wave forms
Applications Of Capacitor
- Capacitor as a Filter: Capacitor is of low pass filter and high pass filter. The reactance of the capacitor is inversely proportional to the frequency. So, we can decrease or increase any circuit at a certain frequency.
- Capacitor as a Discharge Unit: Capacitor has a property of charging and discharging. This application can be used for triggering, ignition and triggering for high scale in power source.
- Snubber Capacitors: It is used to limit the high voltage transient across the circuits.