Coulomb’s Law – Vector Form, Limitation and Examples – NeetHelp

In 1785, Coulomb, on the basis of experiments, gave a law regarding the force acting between two charges.

Defination Of Coulomb’s Law

According to this law, two stationary point-charges repel or attract each other with a force which is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. This force is along the line joining the two charges.

Coulomb’s Law Formula

Formula of vector

In Short : F=kQ1Q2/r2

Where,

  • K is the relative permittivity
  • Q1Q2 are the two point charges
  • r2 is the distance between two point charges

Coulomb’s Law in Vector Form

Vector form of Coulombs law

Some Important Points Regarding Coulombs’ Law

  • Coulomb’s law is based on experimental results, it can not be established theoretically.
  • The law holds only for point charges.
  • The law is applicable for charges at rest (because charges at rest produce electric field only) not first charges in motion(because moving charges produce electric field and magnetic field also).
  • Both the charges exert equal and opposite forces on each other.
  • Force acting between two charges is a central force which acts along the line joining the two charges.
  • The force between two charges is not changed by the presence of other charges.
  • The force between two charges depend upon the magnitude of the two charges, distance between them and upon the nature of the medium between them.

FAQ’s Regarding Coulomb’s Law

What is Coulomb's Law?

According to this law, two stationary point-charges repel or attract each other with a force which is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. This force is along the line joining the two charges.

What is q1 and q2 in Coulomb law?

Q1 and Q2 are the point charges, of which we calculate the force between them.

Why is Coulomb law important?

Coulomb’s law is true for point-charges separated by from very large distance to very small distances such as atomic distances (10-11m) and nuclear distances (10-15m). Therefore it’s not only gives us the force acting between charged body but also help in explaining the forces which bind electrons with nucleus in an atom, two or more atoms in a molecule and several atoms or molecules in solids and liquids.

What is the Unit of charge?

SI Unit of electric charge is “coulomb” and the it’s symbol is “C”.

What is the limitation of Coulomb's law?

There are so many limitations but some important ones are :

  • Applicable only in cases when inverse law works.
  • Applicable only for point charges.
  • It is difficult to apply coulomb law when charge is in arbitrary shape.

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