Electric field strength

Each electric charge surrounds the electric field. As a result of long research, physicists came to the conclusion that the interaction of charged bodies occurs due to the electric fields surrounding them. They are a special form of matter, which is inextricably linked with any electrical charge.

The study of the electric field is carried out by introducing into it small charged bodies. These bodies are called test probes. For example, a charged cork ball is often used as a test charge.

When a trial charge is introduced into the electric field of a body having a positive charge, an easy positive-charged cork ball under its action will deviate more the closer we bring it to the body.

When moving a test charge in the electric field of an arbitrary charged body, it is easy to find out that the force acting on it will be different in different places.

Thus, when the probes q1, q2, q3, ..., qn, which are different in magnitude, are placed in a single point in the field, it is possible to find that the forces acting on them are different, F1, F2, F3, ..., Fn, but the ratio of force to size A definite charge for such a point of the field is unchanged:

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

If we study different points of the field in this way, we obtain the following conclusion: for each single point in the electric field, the ratio of the force acting on the test charge to the value of such charge is invariant and independent of the test charge.

It follows from this that the magnitude of this ratio characterizes the electric field at an arbitrary point of it. The value, which is measured by the ratio of the force acting on the positive charge located at this point of the field, to the charge size and is the electric field strength:

E = F / q1.

It, as can be seen from its definition, is equal to the force that acts on a unit of a positive charge placed in a certain point of the field.

For the unit of electric field strength, the field strength acting on a charge of one electrostatic unit with a force of one dyne is taken. This unit is called the absolute electrostatic unit of tension.

To determine the electric field strength of any point charge q at an arbitrary point in the field A of a given charge spaced from it by a distance r1, it is necessary to place a test charge q1 at this arbitrary point and calculate the force Fa that acts on it (for a vacuum).

According to Coulomb's law :

Fa = (q1q) / r².

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

Ea = q / r².

In addition, one can find the tension at an arbitrary point B; It will be equal to:

Eb = q / r².

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

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

F = qE.

The electric field strength is a vector quantity. The direction of the tension at each particular point of the field will be combined with the direction of the force acting on the positive charge placed in the point.

When a field is formed by several charges: q1 and q2, the intensity E at any point A of a given field will be equal to the geometric sum of the stresses E1 and E2 created separately at the given point by the charges q1 and q2.

The electric field strength at an arbitrary point can be displayed graphically with the help of a directed segment that originates from this point, similarly to the image of force and other vector quantities.