Coulomb's law states that the modulus of force. The Coulomb force is an attractive force if the signs of the charges are different and a repulsive force if the signs of the charges are the same
Topic 1.1 ELECTRIC CHARGES.
Section 1 BASICS OF ELECTRODYNAMICS
1. Electrification of bodies. The concept of charge magnitude.
Law of conservation of charge.
2. Interaction forces between charges.
Coulomb's law.
3. Dielectric constant of the medium.
4. International system of units in electricity.
1. Electrification of bodies. The concept of charge magnitude.
Law of conservation of charge.
If two surfaces are brought into close contact, then available electron transfer from one surface to another, and electrical charges appear on these surfaces.
This phenomenon is called ELECTRIZATION. During friction, the area of close contact of surfaces increases, and the amount of charge on the surface also increases - this phenomenon is called ELECTRICATION BY FRICTION.
During the electrification process, a redistribution of charges occurs, as a result of which both surfaces are charged with charges of equal magnitude and opposite in sign.
Because all electrons have the same charges (negative) e = 1.6 10 C, then in order to determine the amount of charge on the surface (q), it is necessary to know how many electrons are in excess or deficiency on the surface (N) and the charge of one electron.
During the process of electrification, new charges do not appear or disappear, but only occur redistribution between bodies or parts of a body, therefore the total charge of a closed system of bodies remains constant, this is the meaning of the LAW OF CONSERVATION OF CHARGE.
2. Interaction forces between charges.
Coulomb's law.
Electric charges interact with each other while located at a distance, while like charges repel, and unlike charges attract.
First time I found out experienced How does the force of interaction between charges depend? The French scientist Coulomb derived a law called Coulomb's law. Fundamental law i.e. based on experience. When deducing this law, Coulomb used torsion balances.
3) k – coefficient expressing dependence on the environment.
Formula of Coulomb's law.
The force of interaction between two stationary point charges is directly proportional to the product of the magnitudes of these charges and inversely proportional to the square of the distances between them, and depends on the environment in which these charges are located, and is directed along the straight line connecting the centers of these charges.
3. Dielectric constant of the medium.
E is the dielectric constant of the medium, depending on the surrounding medium charges.
E = 8.85*10 - physical constant, dielectric constant of vacuum.
E – relative dielectric constant of the medium, shows how many times the force of interaction between point charges in a vacuum is greater than in a given medium. In a vacuum, the interaction between charges is strongest.
4. International system of units in electricity.
The basic unit for electricity in the SI system is current in 1A, all other units of measurement are derived from 1Ampere.
1C is the amount of electric charge transferred by charged particles through the cross-section of a conductor at a current of 1A in 1s.
q=N; 
Topic 1.2 ELECTRIC FIELD
1. Electric field – as a special type of matter.
6. Relationship between potential difference and electric field strength.
1. The electric field is like a special type of matter.
In nature, an electromagnetic field exists as a type of matter. In different cases, the electromagnetic field manifests itself in different ways, for example, near stationary charges only an electric field manifests itself, which is called electrostatic. Both electric and magnetic fields can be detected near moving charges, which together represent ELECTROMAGNETIC FIELDS.
Let's consider the properties of electrostatic fields:
1) The electrostatic field is created by stationary charges; such fields can be detected
using test charges (small positive charge), because only on them the electric field has a force effect, which obeys Coulomb’s law.
2. Electric field strength.
The electric field as a type of matter has energy, mass, propagates in space with a finite speed and has no theoretical boundaries.
In practice, it is considered that there is no field if it does not have a noticeable effect on the test charges.
Since the field can be detected using force on test charges, the main characteristic of the electric field is tension.
If test charges of different magnitudes are introduced into the same point of the electric field, then there is a direct proportional relationship between the acting force and the value of the test charge.
The coefficient of proportionality between the acting force and the magnitude of the charge is the tension E.
E = formula for calculating the electric field strength, if q = 1 C, then | E | = | F |
Tension is a force characteristic of electric field points, because it is numerically equal to the force acting on a charge of 1 C at a given point in the electric field.
Tension is a vector quantity, the vector of tension in direction coincides with the vector of the force acting on the positive charge at a given point in the electric field.
3. Electric field strength lines. Uniform electric field.
In order to clearly depict the electric field, i.e. graphically, use electric field strength lines. These are lines, otherwise called lines of force, the tangents to which in direction coincide with the intensity vectors at the points of the electric field through which these lines pass,
Tension lines have the following properties:
1) Start in position. charges end on negative, or begin on positive. charges and go to infinity, or come from infinity and end on positive charges..
2) These lines are continuous and do not intersect anywhere.
3) The density of lines (the number of lines per unit surface area) and the electric field strength are in direct and proportional dependence.
In a uniform electric field, the intensity at all points of the field is the same; graphically, such fields are represented by parallel lines at an equal distance from each other. Such a field can be obtained between two parallel flat charged plates at a small distance from each other.
4. Work on moving a charge in an electric field.
Let us place an electric charge in a uniform electric field. Forces will act on the charge from the field. If a charge is moved, work can be done.
Perfect work in areas:
A = q E d - formula for calculating the work of moving a charge in an electric field.
Conclusion: The work of moving a charge in an electric field does not depend on the shape of the trajectory, but it depends on the magnitude of the moved charge (q), field strength (E), as well as on the choice of the starting and ending points of movement (d).
If a charge in an electric field is moved along a closed circuit, then the work done will be equal to 0. Such fields are called potential fields. Bodies in such fields have potential energy, i.e. an electric charge at any point in the electric field has energy and the work done in the electric field is equal to the difference in the potential energies of the charge at the initial and final points of movement.
5. Potential. Potential difference. Voltage.
If charges of different sizes are placed at a given point in the electric field, then the potential energy of the charge and its magnitude are directly proportional.
-(phi) potential of an electric field point
let's accept 
Potential is an energy characteristic of electric field points, because it is numerically equal to the potential energy of a charge of 1 C at a given point in the electric field.
At equal distances from a point charge, the potentials of the field points are the same. These points form a surface of equal potential, and such surfaces are called equipotential surfaces. On the plane these are circles, in space they are spheres.
Voltage
Formulas for calculating the work of moving a charge in an electric field.
1V – voltage between points of the electric field when moving a charge of 1 C, work of 1 J is performed.
- a formula establishing the relationship between the electric field strength, voltage and potential difference.
The intensity is numerically equal to the voltage or potential difference between two field points taken along one field line at a distance of 1 m. The (-) sign means that the voltage vector is always directed towards the field points with decreasing potential.
In this lesson, the topic of which is “Coulomb’s Law,” we will talk about Coulomb’s law itself, what point charges are, and to consolidate the material, we will solve several problems on this topic.
Lesson topic: “Coulomb’s Law.” Coulomb's law quantitatively describes the interaction of stationary point charges - that is, charges that are in a static position relative to each other. This interaction is called electrostatic or electrical and is part of the electromagnetic interaction.
Electromagnetic interaction
Of course, if the charges are in motion, they also interact. This interaction is called magnetic and is described in the section of physics called “Magnetism”.
It is worth understanding that “electrostatics” and “magnetism” are physical models, and together they describe the interaction of both mobile and stationary charges relative to each other. And all together this is called electromagnetic interaction.
Electromagnetic interaction is one of the four fundamental interactions that exist in nature.
Electric charge
What is an electric charge? Definitions in textbooks and the Internet tell us that charge is a scalar quantity that characterizes the intensity of the electromagnetic interaction of bodies. That is, electromagnetic interaction is the interaction of charges, and charge is a quantity that characterizes electromagnetic interaction. It sounds confusing - the two concepts are defined through each other. Let's figure it out!
The existence of electromagnetic interaction is a natural fact, something like an axiom in mathematics. People noticed it and learned to describe it. To do this, they introduced convenient quantities that characterize this phenomenon (including electric charge) and built mathematical models (formulas, laws, etc.) that describe this interaction.
Coulomb's law
Coulomb's law looks like this:
The force of interaction between two stationary point electric charges in a vacuum is directly proportional to the product of their moduli and inversely proportional to the square of the distance between them. It is directed along the straight line connecting the charges, and is an attractive force if the charges are opposite, and a repulsive force if the charges are like.
Coefficient k in Coulomb's law is numerically equal to:
Analogy with gravitational interaction
The law of universal gravitation states: all bodies with mass are attracted to each other. This interaction is called gravitational. For example, the force of gravity with which we are attracted to the Earth is a special case of gravitational interaction. After all, both we and the Earth have mass. The force of gravitational interaction is directly proportional to the product of the masses of interacting bodies and inversely proportional to the square of the distance between them.
The coefficient γ is called the gravitational constant.
Numerically it is equal to: 
.
As you can see, the type of expressions that quantitatively describe gravitational and electrostatic interactions are very similar.
The numerators of both expressions are the product of units characterizing this type of interaction. For gravitational - these are masses, for electromagnetic - charges. The denominator of both expressions is the square of the distance between the objects of interaction.
The inverse relationship with the square of the distance is often found in many physical laws. This allows us to speak about a general pattern connecting the magnitude of the effect with the square of the distance between the objects of interaction.
This proportionality is valid for gravitational, electrical, magnetic interactions, sound force, light, radiation, etc.
This is explained by the fact that the surface area of the sphere of distribution of the effect increases in proportion to the square of the radius (see Fig. 1).
Rice. 1. Increasing the surface area of the spheres
This will look natural if you remember that the area of a sphere is proportional to the square of the radius:
Physically, this means that the force of interaction between two stationary point charges of 1 C, located at a distance of 1 m from each other in a vacuum, will be equal to 9·10 9 N (see Fig. 2).
Rice. 2. The force of interaction between two point charges in 1 C
It would seem that this power is enormous. But it is worth understanding that its order is associated with another characteristic - the amount of charge 1 C. In practice, the charged bodies with which we interact in everyday life have a charge on the order of micro- or even nanocoulombs.
Coefficientand electrical constant
Sometimes, instead of a coefficient, another constant is used that characterizes the electrostatic interaction, which is called the “electric constant”. It is designated . It is related to the coefficient as follows:
By performing simple mathematical transformations, you can express and calculate it:
Both constants, of course, are present in the problem book tables. Coulomb's law will then take the following form:
Let's pay attention to a few subtle points.
It is important to understand that we are talking about interaction. That is, if we take two charges, then each of them will act on the other with a force equal in magnitude. These forces will be directed in opposite directions along a straight line connecting the point charges.
Charges will repel if they have the same sign (both positive or both negative (see Fig. 3)), and attract if they have different signs (one negative, the other positive (see Fig. 4)).
Rice. 3. Interaction of like charges
Rice. 4. Interaction of unlike charges
Point charge
The formulation of Coulomb's law contains the term "point charge". What does this mean? Let's remember the mechanics. When studying, for example, the movement of a train between cities, we neglected its size. After all, the size of the train is hundreds or thousands of times smaller than the distance between cities (see Fig. 5). In this problem we considered the train “material point” - a body whose dimensions we can neglect within the framework of solving a certain problem.
Rice. 5. In this case, we neglect the dimensions of the train
So, point charges are material points that have a charge. In practice, using Coulomb's law, we neglect the sizes of charged bodies in comparison with the distances between them. If the sizes of charged bodies are comparable to the distance between them, then due to the redistribution of charge within the bodies, the electrostatic interaction will be more complex.
At the vertices of a regular hexagon with a side, charges are placed one after another. Find the force acting on the charge located in the center of the hexagon (see Fig. 6).
Rice. 6. Drawing for the conditions of task 1
Let's think: the charge located in the center of the hexagon will interact with each of the charges located at the vertices of the hexagon. Depending on the signs, this will be an attractive force or a repulsive force. With charges 1, 2 and 3 being positive, the charge at the center will experience electrostatic repulsion (see Figure 7).
Rice. 7. Electrostatic repulsion
And with charges 4, 5 and 6 (negative), the charge at the center will have an electrostatic attraction (see Fig. 8).
Rice. 8. Electrostatic attraction
The total force acting on the charge located in the center of the hexagon will be the resultant forces ,,,, and, the modulus of each of which can be found using Coulomb's law. Let's start solving the problem.
Solution
The strength of interaction between the charge located in the center and each of the charges at the vertices depends on the moduli of the charges themselves and the distance between them. The distance from the vertices to the center of the regular hexagon is the same, the modules of the interacting charges in our case are also equal (see Fig. 9).
Rice. 9. The distances from the vertices to the center in a regular hexagon are equal
This means that all forces of interaction between the charge in the center of the hexagon and the charges at the vertices will be equal in magnitude. Using Coulomb's law, we can find this module:
The distance from the center to the vertex in a regular hexagon is equal to the length of the side of the regular hexagon, which we know from the condition, therefore:
Now we need to find the vector sum - for this we choose a coordinate system: the axis is along the force, and the axis is perpendicular (see Fig. 10).
Rice. 10. Axes selection
Let's find the total projections on the axis - let's simply denote the module of each of them.
Since the forces are both co-directed with the axis and are at an angle to the axis (see Fig. 11).
Let's do the same for the axis:
The “-” sign is because the forces are directed in the opposite direction of the axis. That is, the projection of the total force on the axis that we have chosen will be equal to 0. It turns out that the total force will act only along the axis; all that remains is to substitute here only the expressions for the modulus of the interaction forces and get the answer. The total force will be equal to:
The problem is solved.
Another subtle point is this: Coulomb’s law says that charges are in a vacuum (see Fig. 12).
Rice. 12. Interaction of charges in vacuum
This is a really important note. Because in an environment other than vacuum, the force of electrostatic interaction will be weakened (see Fig. 13).
Rice. 13. Interaction of charges in a medium other than vacuum
To take this factor into account, a special value was introduced into the electrostatics model, which makes it possible to make a “correction for the environment.” It is called the dielectric constant of the medium. It is denoted, like the electrical constant, by the Greek letter “epsilon”, but without an index.
The physical meaning of this quantity is as follows.
The force of electrostatic interaction between two stationary point charges in a medium other than vacuum will be ε times less than the force of interaction of the same charges at the same distance in vacuum.
Thus, in a medium other than vacuum, the force of electrostatic interaction between two stationary point charges will be equal to:
The values of the dielectric constant of various substances have long been found and collected in special tables (see Fig. 14).
Rice. 14. Dielectric constant of some substances
We can freely use tabulated values of the dielectric constant of the substances we need when solving problems.
It is important to understand that when solving problems, the force of electrostatic interaction is considered and described in the equations of dynamics as an ordinary force. Let's solve the problem.
Two identical charged balls are suspended in a medium with a dielectric constant on threads of the same length fixed at one point. Determine the charge modulus of the balls if the threads are at right angles to each other (see Fig. 15). The sizes of the balls are negligible compared to the distance between them. The masses of the balls are equal.
Rice. 15. Drawing for problem 2
Let's think: three forces will act on each of the balls - gravity; the force of electrostatic interaction and the tension force of the thread (see Fig. 16).
Rice. 16. Forces acting on the balls
By condition, the balls are identical, that is, their charges are equal both in magnitude and sign, which means that the force of electrostatic interaction in this case will be a repulsive force (in Fig. 16, the forces of electrostatic interaction are directed in different directions). Since the system is in equilibrium, we will use Newton's first law:
Since the condition says that the balls are suspended in a medium with dielectric constant , and the sizes of the balls are negligible compared to the distance between them, then, in accordance with Coulomb’s law, the force with which the balls will repel will be equal to:
Solution
Let's write Newton's first law in projections on the coordinate axes. Let's direct the axis horizontally and the axis vertically (see Fig. 17).
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Page 56
COULLOMB'S LAW (10th grade study, pp. 354-362)
Basic law of electrostatics. The concept of a point charged body.
Measuring the force of interaction between charges using a torsion balance. Coulomb's experiments
Definition of a point charge
Coulomb's law. Formulation and formula
Coulomb force
Definition of charge unit
Coefficient in Coulomb's law
Comparison of electrostatic and gravitational forces in an atom
Equilibrium of static charges and its physical meaning (using the example of three charges)
The basic law of electrostatics is the law of interaction of two stationary point charged bodies.
Installed by Charles Augustin Coulon in 1785 and bears his name.
In nature, point-like charged bodies do not exist, but if the distance between the bodies is many times greater than their size, then neither the shape nor the size of the charged bodies significantly influence the interactions between them. In that case, these bodies can be considered as point bodies.
The strength of interaction between charged bodies depends on the properties of the medium between them. Experience shows that air has very little effect on the strength of this interaction and it turns out to be almost the same as in a vacuum.
Coulomb's experiment
The first results on measuring the force of interaction between charges were obtained in 1785 by the French scientist Charles Augustin Coulomb
A torsion balance was used to measure force.
A small, thin, uncharged golden sphere at one end of an insulating beam, suspended on an elastic silver thread, was balanced at the other end of the rocker by a paper disk.
By turning the rocker it was brought into contact with the same stationary charged sphere, as a result of which its charge was divided equally between the spheres.
The diameter of the spheres was chosen to be much smaller than the distance between them in order to exclude the influence of the size and shape of charged bodies on the measurement results.
A point charge is a charged body whose size is much smaller than the distance of its possible action on other bodies.
The spheres having the same charges began to repel each other, twisting the thread. The angle of rotation was proportional to the force acting on the moving sphere.
The distance between the spheres was measured using a special calibration scale.
By discharging sphere 1 after measuring the force and connecting it again with the stationary sphere, Coulomb reduced the charge on the interacting spheres by 2,4,8, etc. once,
Coulomb's Law:
The force of interaction between two stationary point charges located in a vacuum is directly proportional to the product of the charge modules and inversely proportional to the square of the distance between them, and is directed along the straight line connecting the charges.
k – proportionality coefficient, depending on the choice of unit system.
I call the F12 force the Coulomb force
The Coulomb force is central, i.e. directed along the line connecting the charge centers.
In SI, the unit of charge is not fundamental, but derivative, and is determined using the Ampere, the basic SI unit.
A coulomb is an electric charge passing through the cross section of a conductor at a current of 1 A in 1 s.
In SI, the proportionality coefficient in Coulomb's law for vacuum is:
k = 9*109 Nm2/Cl2
The coefficient is often written as:
e0 = 8.85*10-12 C2/(Nm2) – electrical constant
Coulomb's law is written in the form:
If a point charge is placed in a medium with a relative permittivity e other than vacuum, the Coulomb force will decrease by a factor of e.
For any medium other than vacuum e > 1
According to Coulomb's law, two point charges of 1 C each, at a distance of 1 m in a vacuum, interact with a force
From this estimate it is clear that a charge of 1 Coulomb is a very large value.
In practice, they use submultiple units - µC (10-6), mC (10-3)
1 C contains 6*1018 charges of electrons.
Using the example of the interaction forces between an electron and a proton in the nucleus, it can be shown that the electrostatic force of interaction between particles is approximately 39 orders of magnitude greater than the gravitational force. However, the electrostatic forces of interaction of macroscopic bodies (generally electrically neutral) are determined only by very small excess charges located on them, and therefore are not large compared to gravitational forces, which depend on the mass of the bodies.
Is equilibrium of static charges possible?
Let's consider a system of two positive point charges q1 and q2.
We will find at what point the third charge should be placed so that it is in equilibrium, and we will also determine the magnitude and sign of this charge.
Static equilibrium occurs when the geometric (vector) sum of forces acting on the body is equal to zero.
The point at which the forces acting on the third charge q3 can cancel each other is located on the straight line between the charges.
In this case, the charge q3 can be either positive or negative. In the first case, repulsive forces are compensated, in the second - attractive forces.
Taking into account Coulomb's law, the static balance of charges will be in the case of:
The equilibrium of the charge q3 does not depend either on its magnitude or on the sign of the charge.
When the charge q3 changes, both the attractive forces (q3 positive) and the repulsive forces (q3 negative) change equally.
By solving a quadratic equation for x, we can show that a charge of any sign and magnitude will be in equilibrium at a point at a distance x1 from charge q1:
Let us find out whether the position of the third charge will be stable or unstable.
(In stable equilibrium, a body removed from the equilibrium position returns to it; in unstable equilibrium, it moves away from it)
With a horizontal displacement, the repulsive forces F31, F32 change due to changes in the distances between the charges, returning the charge to the equilibrium position.
With a horizontal displacement, the charge q3 equilibrium is stable.
With a vertical displacement, the resultant F31, F32 pushes q3
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In 1785, the French physicist Charles Auguste Coulomb experimentally established the fundamental law of electrostatics - the law of interaction of two stationary point charged bodies or particles.
The law of interaction of stationary electric charges - Coulomb's law - is a basic (fundamental) physical law. It does not follow from any other laws of nature.
If we denote the charge modules by |q 1 | and |q 2 |, then Coulomb’s law can be written in the following form:
where k is a proportionality coefficient, the value of which depends on the choice of units of electric charge. In the SI system N m 2 / C 2, where ε 0 is the electrical constant equal to 8.85 10 -12 C 2 / N m 2
Statement of the law:
The force of interaction between two point stationary charged bodies in a vacuum is directly proportional to the product of the charge modules and inversely proportional to the square of the distance between them.
Coulomb's law in this formulation is valid only for point charged bodies, since only for them the concept of distance between charges has a certain meaning. There are no point charged bodies in nature. But if the distance between the bodies is many times greater than their size, then neither the shape nor the size of the charged bodies significantly, as experience shows, affects the interaction between them. In this case, the bodies can be considered as point bodies.
It is easy to find that two charged balls suspended on threads either attract each other or repel each other. It follows that the forces of interaction between two stationary point charged bodies are directed along the straight line connecting these bodies.
Such forces are called central. If we denote the force acting on the first charge from the second, and by the force acting on the second charge from the first (Fig. 1), then, according to Newton’s third law, . Let us denote by the radius vector drawn from the second charge to the first (Fig. 2), then
If the signs of the charges q 1 and q 2 are the same, then the direction of the force coincides with the direction of the vector; otherwise, the vectors and are directed in opposite directions.
Knowing the law of interaction of point charged bodies, one can calculate the force of interaction of any charged bodies. To do this, bodies must be mentally broken down into such small elements that each of them can be considered a point. By adding geometrically the forces of interaction of all these elements with each other, we can calculate the resulting interaction force.
The discovery of Coulomb's law is the first concrete step in studying the properties of electric charge. The presence of an electric charge in bodies or elementary particles means that they interact with each other according to Coulomb's law. No deviations from the strict implementation of Coulomb's law have currently been detected.
Coulomb's experiment
The need to conduct Coulomb's experiments was caused by the fact that in the middle of the 18th century. A lot of high-quality data on electrical phenomena has accumulated. There was a need to give them a quantitative interpretation. Since the electrical interaction forces were relatively small, a serious problem arose in creating a method that would make it possible to make measurements and obtain the necessary quantitative material.
The French engineer and scientist Charles Coulomb proposed a method for measuring small forces, which was based on the following experimental fact, discovered by the scientist himself: the force generated during elastic deformation of a metal wire is directly proportional to the angle of twist, the fourth power of the diameter of the wire, and inversely proportional to its length:
where d is the diameter, l is the length of the wire, φ is the angle of twist. In the given mathematical expression, the proportionality coefficient k was determined empirically and depended on the nature of the material from which the wire was made.
This pattern was used in the so-called torsion balances. The created scales made it possible to measure negligible forces of the order of 5·10 -8 N.
The torsion scale (Fig. 3, a) consisted of a light glass rocker 9 10.83 cm long, suspended on a silver wire 5 about 75 cm long, 0.22 cm in diameter. At one end of the rocker there was a gilded elderberry ball 8, and at the other – counterweight 6 – a paper circle dipped in turpentine. The upper end of the wire was attached to the head of the device 1. There was also a pointer 2, with the help of which the angle of twist of the thread was measured on a circular scale 3. The scale was graduated. This entire system was placed in glass cylinders 4 and 11. In the upper cover of the lower cylinder there was a hole into which a glass rod with a ball 7 at the end was inserted. In the experiments, balls with diameters ranging from 0.45 to 0.68 cm were used.
Before the start of the experiment, the head indicator was set to zero. Then ball 7 was charged from the previously electrified ball 12. When ball 7 came into contact with the movable ball 8, charge redistribution occurred. However, due to the fact that the diameters of the balls were the same, the charges on balls 7 and 8 were also the same.
Due to the electrostatic repulsion of the balls (Fig. 3, b), the rocker 9 turned by some angle γ (on a scale 10 ). Using the head 1 this rocker returned to its original position. On a scale 3 pointer 2 allowed to determine the angle α twisting the thread. Total twist angle φ = γ + α . The force of interaction between the balls was proportional φ , that is, by the angle of twist one can judge the magnitude of this force.
With a constant distance between the balls (it was fixed on a scale of 10 in degrees), the dependence of the force of electrical interaction between point bodies on the amount of charge on them was studied.
To determine the dependence of the force on the charge of the balls, Coulomb found a simple and ingenious way to change the charge of one of the balls. To do this, he connected a charged ball (balls 7 or 8 ) with the same size uncharged (ball 12 on the insulating handle). In this case, the charge was distributed equally between the balls, which reduced the charge under study by 2, 4, etc. times. The new value of the force at the new value of the charge was again determined experimentally. At the same time, it turned out that the force is directly proportional to the product of the charges of the balls:
The dependence of the strength of electrical interaction on distance was discovered as follows. After imparting a charge to the balls (they had the same charge), the rocker deviated at a certain angle γ . Then turn the head 1 this angle decreased to γ 1 . Total twist angle φ 1 = α 1 + (γ - γ 1)(α 1 – head rotation angle). When the angular distance of the balls is reduced to γ 2 total twist angle φ 2 = α 2 + (γ - γ 2) . It was noticed that if γ 1 = 2γ 2, TO φ 2 = 4φ 1, i.e., when the distance decreases by a factor of 2, the interaction force increases by a factor of 4. The moment of force increased by the same amount, since during torsional deformation the moment of force is directly proportional to the angle of twist, and therefore the force (the arm of the force remained unchanged). This leads to the following conclusion: The force of interaction between two charged balls is inversely proportional to the square of the distance between them:
Date: 04/29/2015
