A capacitor is an electronic component that is primarily used to store energy in the form of electrical charges. The internal structure of a capacitor consists of two metallic plates that are placed parallel to each other and are separated by a dielectric medium. The fabrication material generally preferred to manufacture the capacitor plates include the conducting metals such as tantalum, aluminium, etc. while the dielectric materials used for insulation purposes include air, vacuum, ceramic, paper, plastic, etc. A capacitor is capable of storing both negative as well as positive electrical charges and falls under the category of passive electronic components. The property that defines the charge storing capacity of a capacitor is known as capacitance and is defined as the ratio of the electric charges that get accumulated across the conducting plates of a capacitor to the potential difference that get developed across the conducting plates due to the accumulation of charges. The units in which capacitance can be measured are Coulombs per Volt and Farads. Farads is the SI unit of measurement of capacitance that is named after the English physicist Michael Faraday. On the basis of type of application, charge storing ability, and the form of the dielectric material used to separate the conductor plates, a capacitor can be subclassified into multiple categories such as a fixed capacitor, variable capacitor, polarized capacitor, non-polarized capacitor, electrolytic capacitor, paper capacitor, ceramic capacitor, mica capacitors, etc.
Examples of Capacitor in Real Life
There are a variety of daily life applications where the use of a capacitor or the demonstration of the principle of capacitance can be observed easily. Some of such examples are listed below:
1. Camera Flash
Camera flash forms one of the most prominent examples of the applications that make use of capacitors in real life. A camera typically requires an enormous amount of energy in a short time duration to produce a flash that is bright and vibrant as desired by the user. Using a battery is not an efficient mode of generating such a huge amount of power, which is why to serve the purpose, an array of capacitors is deployed in the inner circuitry of the camera that tends to store energy supplied by the battery source in form of electric charges. Upon pressing the trigger button or the switch, the capacitor begins to discharge quickly and the charged particles begin to flow towards the light bulb circuit at a rapid rate, thereby generating a flashlight that gets illuminated brightly for a fraction of seconds.
A fan is yet another example of the daily use of gadgets and devices that make use of capacitors for their basic operation. Here, a capacitor typically aids at initiating the rotatory motion of the fan blades and is also responsible to sustain the spinning motion of the moving blades. For this purpose, the capacitor generates the necessary magnetic flux required to produce an adequate magnitude of torque force. The torque or the torsion force is then supplied to the blades of the fan causing the fan blades to rotate about their axis.
3. Emergency Shutdown System for Computers
Capacitors also come in handy in cases of emergency shutdowns. For instance, some of the emergency shutdown systems designed for computers contain an internal electronic circuit that is embedded with an array of capacitors on the output side. Here, the main task of the capacitor is to provide the necessary energy supply that powers up the computer system for a particular duration of time. The discharging rate of the capacitors is quite high and the backup power stays for significantly less duration of time. This means that the user can only manage to save the important files and shut down the system properly with the help of capacitor-based power supply systems. The main advantage of using such systems is the high reliability and minimum requirement of additional charging circuitry. This is because the capacitors get charged automatically when the device is turned on.
4. Audio Equipment
One of the major applications of capacitors lies in signal filtering and manipulation. The process of signal filtering implies removing ripples and spikes from the original input signal and generating a smoothened signal as output. The signal filtering property of capacitors can be utilized for the purpose of noise filtering, which is why capacitors are often used in certain audio equipment and gadgets such as loudspeakers, microphones, woofers, tweeters, etc. Other than the removal of unwanted noise signals, capacitors also help in signal enhancement, amplification, and replication. Capacitors are generally included in the vehicle audio systems to provide additional amplification to the signal whenever the magnitude of the received signal goes below a certain level due to range fluctuations and electromagnetic interference.
5. AC to DC Converters
AC to DC converters are used in almost all electronic gadgets, decides, and circuits including mobile phones, computers, chargers, televisions, industrial machines, consumer electronic gadgets, etc. AC to DC conversion typically involves transforming a pulsating signal into a steady signal by passing the signal through an electronic circuit. To perform the AC to DC conversion, diode rectifier circuits are considered to be quite efficient as the construction and assembly of such circuits is comparatively simpler and they tend to provide large DC output power, less ripple factor, and high-frequency signal. Such circuits generally use the charging and discharging properties of the capacitor for the purpose of reliable conversion of AC signal to DC signal.
6. Energy Storing Devices
A capacitor can be used in place of batteries as an alternative component to store energy. Usually, capacitors are used as energy storing devices in applications where a burst of power is desired. Also, the property of the capacitor to store and release charged particles at a significantly higher rate makes it an efficient temporary energy storing device with a life span that is comparatively more than the traditional batteries or energy devices.
Sensors are the devices that take the physical signal from the surroundings as input, feed the input signal to the processing unit, and produce an output on the basis of the data processing or analysis. There are a variety of sensors available in the market such as proximity sensors, motion sensors, infrared sensors, humidity sensors, etc. Most of the sensors available in the market make use of capacitors and capacitance to conclude a result or provide a steady output. The input signal obtained by the surroundings is fed to the structure of the capacitor. Any type of deformation or change in the original structure of the capacitor tends to alter the capacitance value. The gain or loss in the capacitance value of the capacitor generally depends on the change in the magnitude of distance between the two conducting plates of the capacitor. The change in distance between the capacitor plates is then communicated to the output or display unit of the device and the information is displayed accordingly.
8. Tuning Circuits
Tuning circuits are a crucial part of most analogue electronic devices and gadgets. They are essentially used in volume control and frequency adjusting knobs of traditional radio transmitters and receivers. The internal circuitry that handles the adjustment operation of amplification value or frequency makes use of capacitors and inductors. The charging and discharging of a capacitor through a wire coil leads to the generation of a magnetic field. The magnetic field gets produced when the capacitor is charging and it diminishes when the capacitor discharges. The accumulation and release of the charged particles take place at regular intervals. The frequency at which the charging and discharging takes place corresponds to the frequency of the nearest railway station.
9. Power Factor Correction Systems
In an electric power system, the power factor is basically defined as the ratio of the real power absorbed by the load to the apparent power circulating in the circuit. Since the power factor is a ratio, it is a dimensionless quantity typically ranging between -1 and +1. Power factor correction can be simply defined as a technique of increasing the power factor of a power supply. For this purpose, usually, power factor correction capacitors are used. The value of power factor correction capacitors is usually measured in volt-amperes reactive instead of Farads. Such capacitors tend to provide a leading current that cancels out the lagging current flowing into the circuit, thereby maintaining the value of the power factor as close to unity as possible. The power factor correction capacitors embedded in the power supply systems primarily aim at diminishing the harmonic currents and balancing the inductive loading produced by various devices such as induction motors, electric motors, and transmission lines. If the harmonic current is not eliminated from the circuit, it tends to flow towards the AC power system and damage the equipment, hence the power factor correction capacitors also safeguard the power system.
10. Safety Circuits
As the name itself suggests, a safety circuit is typically deployed in the internal circuitry of electronic devices to safeguard the operation or working of that particular device or gadget. For this purpose, the safety circuits usually make use of the capacitors. Such capacitors are generally known as safety capacitors. Safety capacitors can be used for both domestic as well as commercial purposes. The working principle of most safety capacitors is simple, the capacitive reactance generated by the safety capacitor at a particular value of AC signal frequency helps fix a limit to the maximum value of operating current. If the signal surpasses the threshold level, it gets bypassed or the circuit gets broken up. Some of the most common hazards that a safety capacitor is able to handle include electric shock, explosion, fire, high temperature, energy leakage, radiations, etc. On the basis of the position in which a capacitor is deployed in the internal circuitry of the devices, safety capacitors can be broadly classified into three categories, namely across the line, antenna coupling, and line bypass.
11. Power Conditioning Systems
A power conditioner is a device that is mainly used to protect the gadget connected on the load side of the circuit by smoothing out the noisy input signal, bypassing the voltage fluctuations, and eliminating spikes and transients from the signal flowing through the circuit. The property of capacitors by virtue of which they are able to allow AC signals to pass through them, but block the DC signals serve to be the basic principle of working of power conditioners. Some of the real-life applications where signal conditioning is achieved with the help of capacitors include the utility substations. Here, the capacitors are used to balance the inductive loading generated by the transmission power lines. One of the most important merits of using capacitors for the purpose of signal conditioning is that the capacitors can segregate AC signals from DC signals very easily at a higher rate of efficiency, thereby ensuring the flow of a constant magnitude signal through the circuit.
12. Random Access Memory
RAM or Random Access Memory is the memory element that is used as the primary memory element by most computing devices. RAM is basically is a volatile memory element. This means that the information is retained in the memory only till the device is turned on. Once the device is shut down, the information stored by the random access memory gets lost. RAM or random access memory can be classified into two broad categories, namely, a DRAM, i.e., dynamic random access memory or SRAM, i.e., Static Random Access Memory. A capacitor is one of the main elements contained by the internal structure of the DRAM that helps in the temporary storage of data by generating a trail of binary bits according to the charging or discharging of the capacitor. The device tends to read a high state or a binary value one when the capacitor is fully charged, while the device reads a low state or a binary value 0 when the capacitor is discharged.
13. Charge-Coupled Devices
A charge-coupled device is an integrated circuit that basically comprises an array of interlinked or coupled capacitors. Usually, a charge-coupled device makes use of the capacitor in an analogue form. An external circuit is usually attached to the charge-coupled device or a CCD to control the flow of charges within the circuit. One of the prominent applications where charge-coupled devices are employed is digital imaging.
14. Coupling and Decoupling Circuits
Coupling and decoupling circuits are yet another example of the applications where the application of capacitors can be observed easily. Coupling is the process through which an electrical signal flowing in the circuit is passed on from one part of the circuit to another part. If the energy is coupled from one part of the circuit to the other without passing it through the capacitor, there exist comparatively more chances of device failure, signal loss, and short circuit. Likewise, decoupling circuits make use of capacitors to decouple one part of the circuit from the other, i.e., prevent the electronic signal flowing through the circuit to get circulated among certain portions of subsystems. The decoupling process isolates the different parts of an electronic circuit and helps remove the noise from the circuit. A decoupling capacitor is also known as the bypass capacitor, offers a significantly high magnitude of impedance, and is generally placed between the ground and the power supply.
15. Timing Element
The charging and discharging of a capacitor take place at regular intervals. This particular property of capacitors makes them fit to work as timing circuits or devices. To set the timing of the circuit to a particular amount of time, the capacitor with the appropriate capacitance value is required to be chosen. For this purpose, the charging and discharging time of the capacitor is noted. An indicator device such as a buzzer or an LED is usually attached to the output of timing circuits to indicate the turning on and off of the timing element.
16. Pulsed Input Power and Trigger Systems for Weapons
The ability of capacitors to produce bursts of power in a short amount of time is generally utilised by various pulsed power systems and weapons. Some of the most common devices or gadgets that operated on the pulsed power supplied by a capacitor or an array of capacitors include pulse forming networks, particle accelerators, pulsed lasers, electromagnetic forming, Marx generators, etc. Also, devices such as an exploding bridge wire detonator or a slapper detonator can operate only on high power and fast pulse signals, which is why such devices make use of capacitors as a power source as well. Here, the main aim is to deliver the right amount of power in a short duration of time that is sufficient enough to trigger the detonators. Furthermore, capacitors can also be used as the power sources for electromagnetic rail guns, coil guns, or electromagnetic armour.