Electric field: definition, characteristics, properties

There is such a term in physics as "Electric field". It describes the appearance of a certain force around charged bodies. It is applied in practice and found in everyday life. In this article, we will look at what an electric field is and what its properties are, as well as where it occurs and is applied.

Definition

An electric field arises around a charged body. In simple terms, this is a field that acts on other bodies with a certain force.

The main quantitative characteristic is the electric field strength. It is equal to the ratio of the force acting on the charge to the magnitude of the charge. The force acts in a certain direction, hence the strength of the EP is a vector quantity. Below is the formula for tension:

The EF strength acts in a direction that is calculated according to the principle of superposition. That is:

In the figure below, you see a conventional graphic representation of two charges of different polarity and the lines of force of the electric field arising between them.

Important! The main condition for the appearance of an electric field is that the body must have some kind of charge. Only then a field will arise around him, which will act on other charged bodies.

To determine the magnitude of the electric field strength around a single test charge, use Coulomb's law, in this case:

Such a field is also called the Coulomb field.

Another important physical quantity is the potential of the electric field. This is no longer a vector, but a scalar quantity, it is directly proportional to the energy applied to the charge:

Important! Strength and energy characteristics of an electric field are strength and potential. These are its basic physical properties.

It is measured in Volts and is numerically equal to the work of the EF to move the charge from a certain point to infinity.

You can learn more about what the electric field strength is from the video tutorial:

Types of fields

There are several main types of fields, depending on where it exists. Let's consider several examples of fields that arise in various situations.

1. If the charges are stationary, this is a static field.
2. If the charges move along the conductor, it is magnetic (not to be confused with EF).
3. A stationary field arises around fixed conductors with a constant current.
4. In radio waves, an electric and magnetic field is emitted, which are located in space perpendicular to each other. This happens because any change in the MF generates the appearance of an electric field with closed lines of force.

Electric field detection

We tried to tell you all the important definitions and conditions for the existence of an electric field in simple language. Let's figure out how to find it. Magnetic detection is easy - using a compass.

We can find an electric field in everyday life. We all know that if you rub a plastic ruler on your hair, then small pieces of paper will begin to be attracted to it. This is the action of the electric field. When you take off your woolen sweater, you hear a crackle and see sparks - that's it.

Another way to detect an EF is to place a test charge in it. The valid field will reject it. This is used in CRT monitors and, accordingly, in oscilloscope ray tubes, we will talk about this later.

Practice

We have already mentioned that in everyday life the electric field manifests itself when you remove woolen or synthetic clothes from yourself and sparks slip between hair and wool when you rub a plastic ruler and hold over small pieces of paper, and they attract and other. But these are not normal technical examples.

In conductors, the slightest EF causes the movement of charge carriers and their redistribution. In dielectrics, since the band gap in these substances is large, the electron beam will cause the movement of charge carriers only in the case of a dielectric breakdown. In semiconductors, the action is between the dielectric and the conductor, but it is necessary to overcome the small band gap by transferring energy of the order of 0.3... 0.7 eV (for germanium and silicon).

From what is in every home are electronic household appliances, including power supplies. They have an important part that works thanks to the electric field - this is a capacitor. In it, the charges are held on the plates, separated by a dielectric, precisely due to the work of the electric field. In the picture below you see a conventional image of the charges on the capacitor plates.

Another application in electrical engineering is field effect transistors or MOS transistors. Their name already mentions the principle of operation. In them, the principle of operation is based on a change in the STOK-ISTOK conductivity under the influence of a transverse electric field on the semiconductor, and in MOS (MOS, MOSFET - the same) and the gate is completely separated by a dielectric layer (oxide) from the conducting channel, so that the influence of the GATE-SOURCE currents is impossible due to definition.

Another application that has already disappeared in everyday life, but is still "alive" in industrial and laboratory technology, is cathode ray tubes (CRT or so-called picture tubes). Where one of the options for a device for moving the beam across the screen is an electrostatic deflection system.

In simple terms, there is a gun that emits (emits) electrons. There is a system that deflects this electron to the desired point on the screen to obtain the desired image. A voltage is applied to the plates, and the emitted flying electron is affected by Coulomb forces, respectively, and the electric field. Everything described happens in a vacuum. Then a high voltage is applied to the plates, and a horizontal transformer and a flyback converter are installed to form it.

The video below briefly and clearly explains what an electric field is and what properties this special type of matter has:

Related materials:

• What is dielectric loss
• The dependence of the resistance of the conductor on temperature
• Ohm's law in simple words
• Electrician books