Another important feature of a charged system is its potential energy, PE. The potential energy is generated by the electrostatic interactions between the charge particles and is the same: the model between the electrostatic force and the distance can be characterized as an inverse quadratic relationship. Careful observations show that the electrostatic force between two point charges varies inversely with the square of the distance between the two charges. That is, the factor by which the electrostatic force is modified is the inverse value of the square of the factor by which the separation distance is modified. Thus, if the distance is doubled (increased by a factor of 2), the electrostatic force is reduced by a factor of four (2 is increased at the second power). And if the distance is tripled (increased by a factor of 3), the electrostatic force decreases by a factor of nine (3 increased at the second power). This quadratic effect makes the elimination of a double importance in its effect on the electrostatic force. The force runs along the straight line that connects the two charges. If the charges have the same sign, the electrostatic force between them is repulsive; If they have different signs, the power between them is attractive. In electrostatic units or Gaussian units, the unit charge (esu or statcoulomb) is defined in such a way that the Coulomb constant disappears because it has the value of one and becomes dimensionless. The electrostatic force F2 {textstyle mathbf {F} _{2}} suffered by q 2 {displaystyle q_{2}} according to Newton`s third law is F 2 = − F 1 {textstyle mathbf {F} _{2}=-mathbf {F} _{1}}.
Electrostatics is the part of physics that describes the interactions between stationary charges. You`re probably familiar with Coulomb`s law, the central law of electrostatics. This law states that two charged particles exert a force on each other that is the same: The inverse quadratic relationship between the electrostatic force and the distance is shown in the following table. Since it is an inverted square law, the law is analogous to Isaac Newton`s inverse square law of universal gravity, but gravitational forces are always attractive, while electrostatic forces can be attractive or repulsive. [2] Coulomb`s law can be used to derive the Gaussian law and vice versa. In the case of a single stationary point charge, the two laws are equivalent and express the same physical law in different ways. [5] The law has been extensively tested, and observations have maintained the law on the scale from 10−16 m to 108 m. [5] The inverse quadratic relationship between force and distance is expressed in Coulomb`s equation for electrostatic force.
In the previous section of lesson 3, Coulomb`s law was given as Coulomb`s law in vector form, which states that the electrostatic force F 1 {textstyle mathbf {F} _{1}} experimented by a charge, q 1 {displaystyle q_{1}} at the position r 1 {displaystyle mathbf {r} _{1}} , near another charge, q 2 {displaystyle q_{2}} at position r 2 {displaystyle mathbf {r} _{2}}, is equal in a vacuum[19] The above values illustrate a diagram: if the distance is doubled, the electrostatic force is reduced by a factor of four. For example, the spacing of line 2 is twice as large as the spacing of line 1; and the electrostatic force of row 2 is one quarter of the electrostatic force of row 1. A comparison of line 1 and line 3 shows that with the increase in distance by a factor of three, the force is reduced by a factor of nine. The distance of row 3 is three times greater than that of row 1 and the strength of row 3 is one ninth of that of row 1. A similar comparison of lines 1 and 4 shows that the electrostatic force is reduced by a factor of 16 when the distance is increased by a factor of four. The distance in row 4 is four times greater than in row 1, and the strength in row 4 is one-sixteenth of that in row 1. Coulomb`s law can be expressed as a simple mathematical expression. The scalar shape indicates the size of the electrostatic force vector F between two point charges q1 and q2, but not its direction. If r is the distance between the charges, the amplitude of the force The law states that the amplitude of the electrostatic gravitational attraction or repulsion between two point charges is directly proportional to the product of the charge quantities and inversely proportional to the square of the distance between them,[4] Coulomb`s inverse square law, or simply Coulomb`s law, is an experimental law[1] of physics, which quantifies the amount of force between two electrically charged stationary particles.