Electric charge conservation law: formula and definition

click fraud protection

Electric charge is the ability of bodies to be a source of electromagnetic fields. This is what the encyclopedic definition of an important electrical quantity looks like. The main laws associated with it are Coulomb's Law and Conservation of Charge. In this article we will consider the law of conservation of electric charge, we will try to give a definition in simple words and provide all the necessary formulas.

The concept "electric charge"First introduced in 1875 this year. The wording Coulomb's law states that the force that acts between two charged particles directed in a straight line is directly proportional to the charge and inversely proportional to the square of the distance between them.

This means that by moving the charges 2 times, the force of their interaction will decrease by four times. And this is how it looks in vector form:

Applicability limit of the above:

  • point charges;
  • uniformly charged bodies;
  • its action is valid at large and short distances.

Charles Coulomb's merits in the development of modern electrical engineering are great, but let's move on to the main topic of the article - the law of conservation of charge. He claims that the sum of all charged particles in a closed system is unchanged. In simple words, charges cannot appear or disappear just like that. At the same time, it does not change in time and it can be measured (or divided, quantized) in parts that are multiples of an elementary electric charge, that is, an electron.

But remember that in an isolated system, new charged particles appear only under the influence of certain forces or as a result of any processes. So ions arise as a result of the ionization of gases, for example.

If you are concerned about the question, who and when discovered the law of conservation of charge? It was confirmed in 1843 by the great scientist Michael Faraday. In experiments confirming the conservation law, the amount of charges is measured by electrometers, its appearance is shown in the figure below:

But let's confirm our words with practice. Take two electrometers, put a metal disk on the rod of one, cover it with a cloth. Now we need another metal disc on the dielectric handle. There are three of it on a disk lying on an electrometer, and they become electrified. When the disk with the dielectric handle is removed, the electrometer will show how charged it has become, we touch the second electrometer with the disk with the dielectric handle. Its arrow will also deviate. If we now close two electrometers with a rod on the dielectric handles, their arrows will return to their original position. This suggests that the total or resultant electric charge is zero, and its value in the system remains the same.

Hence follows the formula describing the law of conservation of electric charge:

The following formula says that the change in the electric charge in the volume is equivalent to the total current through the surface. This is also called the "equation of continuity".

And if we go to a very small volume, we get the law of conservation of charge in differential form.

It is also important to tell how charge and mass number are related. When talking about the structure of substances, words such as molecules, atoms, protons and the like are often heard. So the mass number is the total number of protons and neutrons, and the number of protons and electrons in the nucleus is called the charge number. In other words, the charge number is called the charge of the nucleus, and it always depends on its composition. Well, the mass of an element depends on the number of its particles.

Finally, we recommend watching the video, which discusses this whole topic in more detail:

Thus, we briefly examined the issues related to the law of conservation of electric charge. It is one of the fundamental laws of physics along with the laws of conservation of momentum and energy. Its action is flawless and with the passage of time and the development of technology it is not possible to refute its validity. We hope that after reading our explanation, all the key points of this law have become clear to you!

Related materials:

  • Faraday's laws in chemistry and physics
  • What is self-induction
  • Rule of the gimbal, right and left hand
Like(0)I do not like(0)

instagram viewer