Coulomb’s law states that for charged particles or objects that are small compared with the distance between them, the force between the charges varies directly as the product of the charges and inversely as the square of the distance between them.
Coulomb's law is like Newton's law of gravity. But unlike gravity, electric forces can be attractive or repulsive.
The electrical force between any two objects obeys a similar inverse-square relationship with distance. The relationship among electrical force, charges, and distance—Coulomb’s law—was discovered by the French physicist Charles Coulomb in the 18th century.
The SI unit of charge is the coulomb, abbreviated C.
The proportionality constant k in Coulomb’s law is similar to G in Newton’s law of gravitation.
If a pair of charges of 1 C each were 1 m apart, the force of repulsion between the two charges would be 9 billion newtons. That would be more than 10 times the weight of a battleship!
Newton’s law of gravitation for masses is similar to Coulomb’s law for electric charges.Whereas the gravitational force of attraction between a pair of one-kilogram masses is extremely small, the electrical force between a pair of one-coulomb charges is extremely large. The greatest difference between gravitation and electrical forces is that gravity only attracts but electrical forces may attract or repel.
Because most objects have almost exactly equal numbers of electrons and protons, electrical forces usually balance out.
Between Earth and the moon, for example, there is no measurable electrical force.
In general, the weak gravitational force, which only attracts, is the predominant force between astronomical bodies.
Although electrical forces balance out for astronomical and everyday objects, at the atomic level this is not always true.
Often two or more atoms, when close together, share electrons.
Bonding results when the attractive force between the electrons of one atom and the positive nucleus of another atom is greater than the repulsive force between the electrons of both atoms. Bonding leads to the formation of molecules.
