Electrostatic Force: Definition, Formula, and Examples |
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What is the Electrostatic Force?
The electrostatic force is the force of attraction or repulsion between two charged particles. It is also called Coulomb’s force or Coulomb’s interaction. For example, the force between the protons and electrons in an atom is electrostatic and is responsible for the atom’s stability. In chemistry, the electrostatic bonding force is important and binds an ionic molecule. ![]() The laws of electrostatics were discovered by French physicist Charles Augustin de Coulomb in 1785 and are known as Coulomb’s law. Laws Governing Electrostatic Force Coulomb’s LawThe electrostatic force between two charged particles can be quantified by Coulomb’s law. It is usually applied to point charges and gives a relationship between the electrostatic force, the magnitude of the charges, and separation distance. According to this law, the force between the two particles is, Directly proportional to the product of the magnitude of the chargesInversely proportional to the square of the distance between the two chargesSuppose the two charged particles are brought close to one another. There will be an attraction if the charges are opposite, or if one is positive and the other negative. On the contrary, the charges will repel if both of them are positive or negative. In other words, like charges repel and unlike charges attract. Electrostatic Force EquationLet us assume that q1 and q2 are the amounts of charges on the two particles separated by a distance r. According to Coulomb’s law, the electrostatic force between the two charges is given by the following equation. \[ F = \frac{k \hspace{0.1 cm}q_1\hspace{0.1 cm} q_2}{r^2} \]Electrostatic force unit: N (Newton). Here, k is called Coulomb’s constant. Its value is 9 x 109 N.m2.C-2. Generally, q1 and q2 can be positive or negative. When two opposite point charges are placed close to each other, the force is attractive and hence, its sign is negative. The magnitude is merely the value of F without the sign. According to the above equation, F vanishes when r → ∞. Hence, at an infinitely large distance, the electrostatic force is zero. Technically, the range of F is infinite. The work done W by the force F on a particle is the product of the force and the displacement d. W= F x d The work done in displacing the particle from one position to another is independent of the path taken. Hence, the electrostatic force is conservative. ![]() Here are some facts and characteristics of the electrostatic force. Like charges repel, and opposite charges attractDirectly proportional to the product of two point-chargesInversely proportional to the distance of separation between the chargesActs along the line joining the two charges Examples of Electrostatic Force in Daily LifeThe electrostatic force is felt in everyday life situations. Here are a few examples, along with images. ![]() ![]() ![]() Here are a few common applications of the electrostatic force. PhotocopierLaser and ink-jet printersVan der Graaff generatorSmoke precipitator andCCD camera Difference between Electrostatic and Gravitational ForcesThe electrostatic force and gravitational force are both fundamental forces of nature. There are a few similarities between the two as both follow the inverse-square law. However, there are also some critical differences. ![]() Problem 1. What is the ratio of electrostatic force and gravitational force of two electrons? Solution. The ratio of electrostatic force to the gravitational force of two electrons is given by FE/FG = ke2/Gme2 = 9 x 109 N.m2.C-2x (1.6 x 10-19)2 C2/6.67 x 10-11 N.m2.kg-2x (9.1 x 10-31)2 kg2 = 4 x 1042 Therefore, the relationship between the gravitational force and the electrostatic force is FE = 4 x 1042 FG Problem 2. If the electrostatic force between two charges is 124 N. What is the distance of separation between the charges, if the charges are 4 μC and 9 μC? Given k = 9 x 109 N m2.C-2. Solution. We shall use the following equation. F = k q1 q2/r2 Given, q1 = 4 x 10-6 C, q2 = 9 x 10-6 C, F = 124 N and k = 9 x 109 N m2.C-2. Putting these values, 124 N =9 x 109 N m2.C-2 x 9 x 10-6 C x 4 x 10-6 C / r2 Or, r2 = 9 x 109 N m2.C-2 x 9 x 10-6 C x 4 x 10-6 C / 124 N = 0.00261 m2 Or, r = 0.05 m References Phys.libretexts.orgIas.ac.inEducation.vic.gov.auPhys.ufl.eduCsun.eduSfu.caEcee.colorado.eduPressbooks-dev.oer.hawaii.eduArticle was last reviewed on Friday, February 17, 2023 |
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