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Essentially, a capacitor is composed of two guides carrying charges with inverse signs yet of equivalent size. A capacitor’s capacitance C is determined by the voltage difference V between each conductor and the charge Q on that conductor. C = Q/ V
There is no external source of charge or potential difference that affects capacitance. It is determined only by the geometry of the conductor. The variety of sizes and shapes of capacitors makes them suitable for a wide range of applications in electronics.
Working of a capacitor
In its most basic form, parallel plate capacitors consist of two parallel conducting plates separated by a dielectric. One plate (plate-I) of a battery (DC Voltage Source) is connected to the positive end of the capacitor and the other plate (plate-II) is connected to the negative end. Plate-I has a positive potency compared to plate-II when the battery’s potential is applied across that capacitor. Current from the battery attempts to flow through this capacitor from the positive plate (plate-I) to the negative plate (plate-II) at a steady-state, but it is unable to do so because the plates are separated by a substance that acts as an insulator.
As time passes, an electric field appears across the capacitor and the positive plate (plate I) accumulates positive charge from the battery, while the negative plate (plate II) accumulates negative charge. With regard to this voltage, a capacitor is capable of storing the maximum amount of charge according to its capacitance after a specific period of time and this period is referred to as the capacitor’s charging time.
Upon removing the battery from the capacitor, the two plates retain the positive and negative charge, which allows the capacitor to serve as an electrical energy source.
The capacitor’s discharge time is calculated based on the time it takes for all charges to disappear from both plates when a load is attached to both ends (plate I and plate II).
Functions of Capacitors
- To store electric potential energy
- Filtering off frequencies that aren’t wanted
- When connected with resistors, voltage changes are delayed
- It is used as a sensing device
- Used in the vehicle’s audio system.
- To distinguish between AC and DC
Energy stored in a capacitor
The capacitance of capacitors refers to the amount of accumulated electrical charge stored on the plates. Like batteries, when a capacitor is connected to a power source, it stores energy that can be released when the capacitor is unplugged. The difference between a battery and a capacitor is that batteries store energy through electrochemical reactions, while capacitors simply store charge. Because chemical processes take longer than electrochemical reactions, capacitors can release stored energy at a faster rate than batteries.
The amount of energy stored in a capacitor depends on how much charge is stored on the plates.
The formula of calculate the energy stored in a capacitor
There are three methods to express the energy stored in a capacitor:
Where,
Q is the charge,
V is the voltage, and
C is the capacitance of the capacitor.
When the charge is in coulombs, the voltage is in volts, and the capacitance is in farads, the energy is in joules.
Application of capacitor energy
Capacitors are employed in electrical circuits in a variety of ways in today’s world. Even though all capacitors serve the same basic purpose, different capacitor shapes are used to achieve distinct circuit functionalities. The following are some of the several capacitor applications in various electrical industries:
- Energy Storage: As a result of its connection to an electric circuit, a capacitor’s primary function is to store electric energy, as well as to use that stored energy as a temporary battery, even if it is not connected. Typical electric devices use capacitors to manage the battery power while changing the batteries, aiding in preventing data loss when changing the batteries.
- Pulsed power and weapons: Various pulsed power devices require capacitors that are specially designed with low inductance and an extremely high voltage to meet large electric current levels. It is possible to store electromagnets, generators (such as Marx generators), pulsed lasers and particle accelerators in these devices.
- Power conditioning: Power conditioning uses capacitors and capacitors are commonly employed in power supplies to smooth out the results of a full-wave or half-wave rectifier. The use of capacitors also allows pump circles to be charged because they produce greater voltages and thus aid in storing energy elements.
- Power factor correction capacitors: Power factor adjustment is commonly performed using capacitors in electricity distribution systems. Instead of farads, the capacitor’s units are generally computed as VAr (volt-amperes reactive). Essentially, inductive loading from appliances such as motors (induction or electric) and transmission lines is minimised to make the load appear primarily resistive.
- Capacitor safety: Unless properly managed and handled, capacitors are capable of storing large amounts of energy that are potentially hazardous. An extended period of time without the power supply could result in this huge level of energy causing fatal shocks and potentially destroying the equipment. You should always discharge the capacitors of all electrical equipment before using it as a precaution.
Conclusion
In this article, we learned about the capacitor and its working in an electric circuit, which is generally used to store electrical energy temporarily. We also saw how the capacitance is affected and learned about the factors that affect the capacitor’s efficiency and the equation that would determine the charge in the circuit and the equivalent capacitors. Also discussed are the uses of a capacitor in real life and how it is utilised in electrical appliances along with its unique functionality.
