Physics Electrostatics chapter 1[electric charges and fields]{part 1}

Electric charges and fields

*Electron theory of electricfication

According to this theory, a body can be charged by the transfer of electrons. Every material is composed of atoms. In an atom, the number of positivity charged protons must be equal to the number of negatively charged electrons.

* SI unit of electric charge: Coulomb

The unit of charge is 'coulomb' and its symbol is C. The column is is defined on the basic of ampere. The rate of flow of electric charge through a conductor is called 'electric current'.

If a conductor carries a current of 1 ampere for 1 second, then the charge that flows through  the conductor will be 1 COULOMB,.

*Three important properties of electric charge

(1) Quantization of electric charge  - The value of elementary charge is too small and we come across long amount of charge in routine experiment etc, we do not experience the quantization of charge in daily life.

(2) Conservation of electric charge - the total amount of charge is an isolated remain constant. Its means that charge can neither be created nor be destroyed.

(3) Invariance Property of charge- This property states that the value of charge does not change the velocity.

**Coulomb's Law: Force between two point -charges

Two stationary point charges repel or attract each other with a force which we directly proportional to the product of the charge and inversely proportional to the square of distance between them. This force is along the line joining the two charges.

*Columbus law in vector form.

Force is a vector quantity as it has both magnitude and direction. The Coulomb's lawcan be re-written in the formof vectors. ... Let the force on the q₁ charge due to q₂ be F₁₂ and force on q₂ charge due to q₁ charge be F₂₁. The corresponding vector from q₁ to q₂ is r₂₁ vector.

#Coulomb's is based on experimental results, it cannot be established theoretically.

Physics Electrostatic chapter 1 [electric charges and field] {part 2}