Electric Field and Application in Capacitors

What is an electric field?

An electric field is a special state of space that exists around a charged particle. This special state affects all charged particles placed in the electric field. The true nature of the electric field, and the true nature of the charge, remains unknown to scientists, but the effects of the electric field can be measured and predicted using known equations.

Just as a magnet produces an invisible magnetic field around it that can be detected by placing a second magnet in its magnetic field and measuring the attractive or repulsive forces acting on the magnet, the electric field produced by an electric charge can be detected by testing the charge. When the test charge is placed within the electric field, an attractive or repulsive force acts on the electric field. This force is called the Coulomb force. In reality, magnetic and electric fields are not completely separate phenomena. A time-varying magnetic field produces - or "induces" - an electric field, while a moving electric field causes a magnetic field as a direct result of motion. Because the two fields are so closely connected, the magnetic and electric fields are combined into a unified electromagnetic field.

Electric Field Definition

An electric field can be defined as a vector field that describes the relationship between the charge of a test particle introduced in the field and the force exerted on that charged test particle.

Application of Electric Fields in Capacitors

Electromagnetism is the science that studies electrostatic and kinetic charges, electric and magnetic fields, and their various effects. Capacitors are devices that use electric fields to store electric potential energy. Therefore, capacitors are governed by the rules of electromagnetism. This article will define and outline some of the terms needed to understand the workings of capacitors. In this article, the electric field will be considered to be uniform at all points in space.

Electric Potential Energy

Electric potential energy is the potential energy of a charged particle in an electric field, which is generated by the Coulomb force acting on the particle. It is defined as the negative of the amount of work required to bring the particle from a reference point (usually infinitely far away) to the point in space where the potential energy is measured. The unit of electric potential energy is the joule [J], the same unit as work in physics.

Electric Potential

Electric potential, also known as electric field potential, is the potential energy that a charged particle has at a point in space. Voltage, also known as the potential difference between two points in space, is the difference in potential between these two points. The unit used for electric potential is the volt [V], named after the Italian physicist Alessandro Volta. The same unit is used for voltage. The potential between two points in a uniform field is the negative of the difference in field strength between those two points.

Electric Field Strength

In a simple parallel plate capacitor, a voltage applied between two conducting plates produces a uniform electric field between those plates. The electric field strength in a capacitor is proportional to the applied voltage and inversely proportional to the distance between the plates. This factor limits the maximum voltage rating of the capacitor, since the electric field strength must not exceed the breakdown field strength of the dielectric used in the capacitor. If the breakdown voltage is exceeded, an arc is generated between the plates. Such an arc can instantly destroy certain types of capacitors. The standard unit used for electric field strength is the volt per meter [V·m-1].

Capacitance

Capacitance represents the ability of a body to store an electric charge. This ability is used in capacitors to store electrical energy by maintaining an electric field. When a voltage is applied to a capacitor, a certain amount of positive charge (+q) accumulates on one plate of the capacitor, while an equal amount of negative charge (-q) accumulates on the other plate of the capacitor.

Where C is the capacitance, q is the amount of charge accumulated on the plates, and V is the voltage across the two plates of the capacitor.

Capacitance is a function of the geometry of the capacitor. Factors such as the area of the plates, the distance between the plates, and the dielectric constant of the dielectric used in the capacitor construction all affect the resulting capacitance. In simple parallel plates, the capacitance is directly proportional to the area and dielectric constant of the plates, and inversely proportional to the distance between the plates. The unit used for capacitance is the farad [F], named after Michael Faraday, a pioneer in the study of electricity and magnetism.

Energy stored on a capacitor

A capacitor is a device used to store electrical energy in an electrical circuit. The energy supplied to a capacitor is stored in the form of an electric field, which is generated between the plates of the capacitor. When a voltage is applied across a capacitor, a certain amount of charge accumulates on the plates.