Coloumbs Law of Electrostatic Force & Relative Permittivity

Hello all Today I am going to post about the topic Coloumbs law Of Electrical Force

Coloumbs Law of Electrical Force :
According to this law The electrostatic force between two point charges is directly proportional to the product of their magnitudes and inversily proportional to the square of distance between their centres

This force will be repulsive or attractive depending upon whether the charges are like or unlike further
The force always acting along the line joining the centres of two charges

Consider two point charges Q1 and Q2 hold "d" distance apart in vacuum
According to Coloumbs law the magnitude of electrostatic force between the charges is given by

Where 'k' is a Constant whose value depends upon the system of units employed and the nature of the medium

The SI units when placed in vacuum

k= 1/(4πε0)
=1/(4π×8.854×10^(-12))

=9×10^9

Where
ε0= Absolute Permittivity of space
=8.854×10^(-12) F/M

F= (1/4πε0)×(Q1Q2/d^2)

*The direction of forces that one charge exerts on another is determined by considering the relative signs of charges

Relative Permittivity Or Dielectric Constant

Permittivity is the property of a medium and effects the magnitude of force between two point charges

•Air or vaccum has minimum values of Permittivity

The absolute Permittivity of all other insulating materials is greater than 'ε0'

εr = ε/ε0
=Absolute Permittivity of the medium / Absolute Permittivity of the Air or Vaccum

Then
Force
F=(1/4πε0εr)×(Q1Q2/d^2)

Hence , relative Permittivity (or Dielectric Constant) of a medium may be defined as the ratio of force between two charges separated by the same distance in the medium