Reference and Education

Electric field potential and its calculation

The potential of an electric field is a scalar value of a body that characterizes the intensity. Electrical power is expressed in terms of a specific parameter. An important property of an electric field, which does not contain vortices and is formed by immovable sources, is its potentiality. Scientists have been thinking about the features of electric and magnetic fields for a long time until their essence has become fully clear.

The real value of the electric field

Scientists have been studying the secret of electricity for a long time. The main reward in her research goes to Oersted. His main discovery was the first experimentally established connection between electrical and magnetic phenomena in 1819-1820.

It became clear that oscillations presuppose a superposition of time-varying electric and magnetic fields. The magnetic intensity vector is perpendicular to the electric vector connected through a long medium. Electrostatic action is an action through the field.

Features of the impact:

  • Each electric charge creates an electrostatic field around itself.
  • An electric field is a space in which voltage forces act.
  • The quantities characterizing the field at this point are intensity and potential.

The intensity of the electrostatic phenomenon at this point is the ratio of the electric force acting on the test charge (positive) placed at this point to the value of this charge:

E = F / q (vector over E and F).

The unit of electrostatic field strength is 1 N / C.

The electric field strength at this point always has a recoil in accordance with the direction of the force acting on the positive test charge.

The value of the strength of the electrostatic field

The value of the strength of the electrostatic field at a distance R from the source Q can be denoted by a simple formula: E = k | Q | / R2.

For a graphical representation of the field, lines are used – curves for which the intensity vector at each point has a tangent part. A field with spherical symmetry is called central. If the lines are parallel to each other, and the intensity has the same value at each point, then the field is called uniform.

The potential difference in physics at the moment is the ratio of the energy of a point positive test weight placed at this point to the value of this charge: V = Ep / q.

The unit for measuring the potential of an electric field point is 1 V (volt).

The potential of the electric field, the formula at a distance R from the source Q can be calculated: V = k Q / r.

Charge around an object

Of course, one can speak of a field if there is any source of it. Each electric body creates a gradient of the electric field potential around itself. Compared to gravitational fields, there is an important difference:

  • Gravitational forces are gravitational forces and can be measured.
  • The forces of electricity can be both attractive and repulsive.

Charge around an object

It is known that the field lines refer to the force vectors acting on the body at this point. Scientists agreed that the arrows of the field line will expose the inverse vector of the force acting on the negative charge. Consequently, the lines of force “come out” of the positive charges and “run” to the negative energy charges.

Electric field strength

In an electric field, as well as in a gravitational field, the concept of tension arises. This indicates what force will act, and it is known that this force depends on the source and on the distance. It is the intensity that is the characteristic of this field that can be charged. By definition, the strength of an electric field is the ratio of the force acting on its value.

In order for the charge system to move at the same speed, you need to constantly act on it with an effort that balances the Culomb value. But along with a change in the distance from the source, this force changes inversely with the square of the distance. You need to use the average value acting on the test charge.

To determine whether the work is positive or negative, you need to think about what is the angle between the vector of the applied force and the vector of displacement. If the test charge is attracted by the source of the field, and the work being done moves that charge closer to the source, then the attraction must be balanced.

In short, an effort is applied that creates a 180 ° displacement with the vector. If cos (α) = -1, then the work is negative. But if the source interacts with the load in such a way as to balance the force parallel to the displacement chain, so that the condition α = 0 °, i.e. cos (α) = 1, the work is positive.

Potential energy

When calculating the potential energy of the test charge at this point of the field, the property is used, in which the difference in potential energy at two points is equal to the work performed when moving this value from one point to another (the same was done, including the energy in the gravitational field).

In order to calculate the potential energy at this point, you need to move the test charge to a place where the potential is zero. Such a place is located at a point infinitely distant from the source. The positive or negative sign of the potential is chosen depending on whether the load with the source is repelled or attracted. If the source charge is negative, then finding the electrostatic potential is the same. When the source is positive, so is the potential.

Equipotential surfaces

If we assume that the source of the electric field is a pointwise charged particle (i.e., the field is central), it follows that all points in space that are equally far from it have the same potential. In space, the set of such points forms the surface of the ball, and the source charge is in the center of the sphere.

However, if the electric field is not centralized, it is still possible to assign surfaces such that a test charge placed at any point on this surface will have the same potential. For example, in the case of a uniform field, such a surface is any plane perpendicular to the field line.

Dielectrics in electrostatics

In addition, the guides have one more group of bodies – these are dielectrics. First you need to clarify the difference between a dielectric and a conductor. Conductors are bodies in which charges can move freely. An example of a conductor is copper wire. If you put a load on it and then touch it with your hand, then this load will “float” out of the conductor and, therefore, unload it.

But if you positively electrify glass, which is a dielectric, then touching it through the hand will not lead to its discharge. The electrons from the limb will only flow at the point of contact, but this glass will still be electrified wherever it is touched.

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