Each electric charge is surrounded by an electric field.As a result of lengthy research physicists have concluded that the interaction of charged bodies is due to the electrical fields surrounding them.They are a special form of matter, which is inextricably linked with all electric charge.

study of the electric field is carried out by introducing a small charged bodies.These bodies are referred to as "test charges".For example, often used as a test charge charged pith ball.

When making a test charge in an electric field of the body, which has a positive charge, light positively charged pith ball under its influence will deviate the more, the closer we will bring it to the body.

When moving a test charge in an electric field of arbitrary charged body can easily discover that the force acting on it, will be different in different places.

Thus, when placed sequentially in one point of the field of different size test positive charges q1, q2, q3, ..., qn is possible to detect that the forces acting on them, F1, F2, F3, ..., Fn vary, but the ratio of theto the size of a specific charge for this point invariably field:

F1 / q1 = F2 / q2 = F3 / q3 = ... = Fn / qn.

If in this way we will explore different points of the field, we get the following conclusion: for every single point in the electric field the ratio of the force acting on a test charge to the amount of such charge and consistently regardless of the magnitude of the test charge.

This implies that the value of this ratio characterize the electric field in any of its points.The value which is measured by the ratio of force exerted on a positive charge placed at that point of the field, to the size of the charge and the electric field is:

E = F / q1.It

, as is clear from its definition, equal to the force acting on a unit positive charge placed at a specific point of the pitch.

The unit of electric field strength taking the field strength acting on the charge size of one unit with an electrostatic force in a din.This unit is called the absolute electrostatic unit of tension.

To determine the electric field intensity of any point charge q at an arbitrary point in the field A of the charge that is separated from it by a distance r1, this should be placed in an arbitrary point test charge q1 and to calculate the force Fa, which acts on it (for vacuum).

According to Coulomb's law:

Fa = (q1q) / r²₁.

If we take the ratio of the force that affects the charge to its value q1, then you can calculate the electric field intensity at point A:

Ea = q / r²₁.

also possible to find the intensity at a point B;it will be equal to:

Eb = q / r²₂.

Therefore, the electric field intensity of a point charge at a particular point of the field (in vacuo) to be directly proportional to the size of the charge and inversely proportional to the square of the distance between this point and the charge.

The field strength acts as its power characteristics.Knowing her at an arbitrary point of E, and is easy to calculate the force F, acting on a charge q at a given point:

F = qE.

electric field - size vector.The direction of the tension in each particular point of the field will be combined with the direction of the force exerted on a positive charge placed at point.

In the formation of the field several charges: q1 and q2 - intensity E at any point A of this field will be equal to the geometric sum of the voltage E1 and E2 generated at that point separate charges q1 and q2.

electric field at any point can be displayed graphically by a directed segment that originates from this point, similar to the image of strength and other vector quantities.