A capacitor is a device that can temporarily store an electric charge.
Capacitors are widely used to build different types of electronic circuits. A capacitor is a passive two-terminal electrical component that can store energy in an electric field electrostatically. In simple terms, it works as a small rechargeable battery that stores electricity. However, unlike a battery, it can charge and discharge in the split of a second.
1. Composition
Capacitors come in all shapes and sizes, but they usually have the same primary components. There are two electrical conductors or plates separated by a dielectric or insulator stacked between them. Plates are composed of conducting material such as thin films of metal or aluminum foil. A dielectric, on the other hand, is a non-conducting material such as glass, ceramic, plastic film, air, paper, or mica. You can insert the two electrical connections protruding from the plates to fix the capacitor in a circuit.
2. How Does It Work?
When you apply a voltage over the two plates or connect them to a source, an electric field develops across the insulator, causing one plate to accumulate positive charge while negative charge gets collected on the other. The capacitor continues to hold its charge even if you disconnect it from the source. The moment you connect it to a load, the stored energy will flow from the capacitor to the load.
Capacitance is the amount of energy stored in a capacitor. The higher the capacitance, the more energy it can store. You can increase the capacitance by moving the plates closer to each other or increasing their size. Alternatively, you can also enhance the insulation qualities to increase the capacitance.
3. Function and Significance
Though capacitors look like batteries, they can perform different types of functions in a circuit such as blocking direct current while allowing alternating current to pass or smooth the output from a power supply. They are also used in electric power transmission systems to stabilize voltage and power flow. One of the most significant functions of a capacitor in the AC systems is power factor correction, without which you can’t provide sufficient amount of starting torque to single phase motors.
Filters Capacitor Applications
If you are using a microcontroller in a circuit to run a specific program, you don’t want its voltage to drop as that will reset the controller. That’s why designers use a capacitor. It can supply the microcontroller with the necessary power for a split second to avoid a restart. In other words, it filters out the noise on the power line and stabilizes the power supply.
Hold-Up Capacitor Applications
Unlike a battery, a capacitor releases its charge rapidly. That’s why it is used to provide power to a circuit for a short while. Your camera batteries charge the capacitor attached to the flash gun. When you take a flash photograph, the capacitor releases its charge in a split second to generate a flash of light.
Timer Capacitor Applications
In a resonant or time-dependent circuit, capacitors are used along with a resistor or inductor as a timing element. The time required to charge and discharge a capacitor determines the operation of the circuit.
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