Kapasîtor Piştgir: Pêşnûmayî, Formul û Tavancên Karvêjan

A parrallel plate capacitor deviceyek e ku hewceş bazekelektrikî û enerciyê di şekilê de ya electric field anîn da li navbera du pelên şarayiyan. Pelan ji bohêtina berdariya ve tiştin û bi voltage source, wisa battery. Navbera pelan dikarin bi hawê, vacuum, an materialî dielectric pêkandin, ku insulator e ku dikarin bi electric field polarized be.

Çi ye Parallel Plate Capacitor?

Parrallel plate capacitor ya definiye kirin ê di rêza du pelên sermetan de qad A û charge Q berdariyê, ji bohêtina d tiştin. Pelan bi voltage source V tiştin, ku difference electric potential di navbera wan de afirand. Electric field E di navbera pelan de uniform û perpendicular e pelan, wisa Figure 1.

Electric field E di navbera pelan de:

li vir V voltage across plates, d separation between plates, σ surface charge density on each plate, and ϵ0 permittivity of free space.

Electric field E induces polarization P in dielectric material, which is dipole moment per unit volume of material. Polarization P reduces effective electric field E inside dielectric and increases capacitance C of capacitor.

Capacitance C of parallel plate capacitor is ratio of charge Q on each plate to voltage V across plates:

Capacitance C depends on geometry of plates and dielectric material between them. For parallel plate capacitor with air or vacuum between plates, capacitance C is given by:

where A area of each plate and d separation between plates.

For parallel plate capacitor with dielectric material between plates, capacitance C is given by:

where k relative permittivity or dielectric constant of material, which is dimensionless quantity that measures how easily material can be polarized by electric field.

Relative permittivity k of dielectric material is always greater than or equal to 1. Higher value of k, more charge can be stored on capacitor for given voltage, and thus higher capacitance.

Endamên Parrallel Plate Capacitors

Parrallel plate capacitors have many applications in various fields of science and engineering. Some of them are:

• Filtering: Parrallel plate capacitors can be used to filter out unwanted frequencies or noise from electrical signal. For example, they can block direct current (DC) signals and allow alternating current (AC) signals to pass through. They can also be used to smooth out voltage fluctuations in power supplies.

• Tuning: Parrallel plate capacitors can be used to tune electrical circuits to resonate at desired frequency. For example, they can be used in radios, televisions, and other communication devices to select specific channel or frequency band.

• Sensing: Parrallel plate capacitors can be used to sense physical quantities such as pressure, temperature, humidity, displacement, etc. For example, they can be used in microphones, thermometers, hygrometers, accelerometers, etc. Capacitance of parrallel plate capacitor changes with these physical quantities due to changes in distance between plates or dielectric material between them.

• Energy storage: Parrallel plate capacitors can be used to store electrical energy in their electric fields. For example, they can be used in flashlights, cameras, defibrillators, etc. Energy stored in parrallel plate capacitor is given by:

where U energy stored in joules (J), C capacitance in farads (F), and V voltage in volts (V).

Summary

• Parrallel plate capacitor is device that can store electric charge and energy in electric field between two conductive plates separated by distance.

• Capacitance of parrallel plate capacitor is proportional to area of each plate and inversely proportional to distance between them. It also depends on dielectric material between plates, which reduces effective electric field and increases capacitance.

• Parrallel plate capacitors have many applications in filtering, tuning, sensing, and energy storage. They can be used to block or pass certain frequencies, select desired frequency, measure physical quantities, and store electrical energy.

Source: Electrical4u.

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