Coulomb's law, the history of discovery and a simple explanation

Significance of the discovery of the fundamental Coulomb's law simply can not be overstated, because on this basis built all the electronics, so to know and understand the more you just need any modern man. In this article I will try to explain as simply the essence of the law, so that Sit back and start.

Historical reference

In fairness, we want to say that the interaction of electric charges observed by many scientists and experimenters before Sh Coulomb. For example, an Englishman Cavendish just after a series of experiments came to the conclusion that the fixed charges interact according to a certain law, but its conclusions he had not made public.

In addition, research in this area involved:

1. GV Richman

2. F. Aepinus

3. D. Bernoulli

4. D. Robinson

In fact, the list is long and all these scientists were close to the opening, but failed to mathematically express their guesses.

Pendant also conducted rigorous measurement. And for his experiments he invented a special torsion balance.

Established design is highly sensitive and responsive to force of the order of 10 -9 Newton. By applying such a small force of the rocker arm rotated by exactly 1 degree. As a result, calculating the angle of rotation, it was possible to measure the applied force.

Just Pendant put forward the idea, which was that at the time of contact with the charged sphere uncharged ball charge is distributed equally among them. In this step the device was reacted by turning on a beam angle.

Thus grounding rigidly fixed ball pendant leveled charge therein. Repeating the process of redistribution and removal of charge, the experimenter reduced initial charge unfixed ball multiple times.

Calculating the deflection angle after each such distribution scientist found regularity in repulsive force action. This gave impetus to the formulation of the well-known law.

we formulate the law

Now, let's formulate Coulomb's law:

Pendant has conducted experiments with spheres of negligible size compared to the distances between them. Such a body in physics still refer to point. And the result was formed the following definition:

In vacuo interaction force between two charged bodies is directly proportional to the product of their modules and inversely proportional to the square of the distance therebetween.

As for me it is not clear, though briefly. More clear can be formulated as follows:

The greater the charge have the body and the closer they are to each other, the greater the force. And if the distance between these bodies increased, the strength will be less.

The mathematical formulation is expressed as:

A force vectors are directed to each other, if the charges and opposite charges to each other, if charges of the same name.

For operation of the law must be met a number of very important conditions:

1. It must be complied with the condition of a point charge.

2. body charged must be still.

3. The law is valid for vacuum and air pollution.

If you look closely at the picture with the formula, you will see a "K" - the coefficient of proportionality, let's talk about it in more detail.

The coefficient of proportionality

This coefficient "K" required for the approval of proportionality in SI (international system of measurement). In this same system for measuring the charge unit receiving pendant - charge quantity of leaked through the conductor with a current of 1 ampere per second.

Remember! Reacting several bodies with a certain charge in the closed system, the total strength of the interaction will be equal to the vector sum of all the charged bodies. In this system, charges will not disappear, and continuously transferred from one to another charged object.

Coulomb's law and dielectrics

This formula is valid in the case when charges are located in vacuo. In any other environment, the strength of interaction between charged bodies inevitably decreases as the polarizing effect is shown. And the change is proportional to a certain value for each environment, which is called - the dielectric constant (permittivity). Given this setting, the permeability coefficient becomes

Limitation in use

I want to emphasize that the very small distances (when the interactions of elementary particles) of about 10 -18 meters, strictly speaking, Coulomb's law is not working.

In addition, this law has clear violation in strong electromagnetic fields (10-18 V / m). In the present environment is not Coulomb potential decreases inversely and exponentially.

Coulomb's law - this is the first fundamental law of the quantitative, mathematically grounded, and its value is difficult to overestimate. It is a discovery of the law can be said that launched the era of the study of electromagnetism.

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