what is the coloumbs law?coloumbs law equation explaination,mathematical problems on coloumbs law.

Do you want to know coloumbs law of electrostatic?

 Coloumbs first law, 

i)Same charges repel to each other.

ii)Opposite charges attract to each other.

 

Coloumbs second law ,

Force between two charges is directly proportional to 

 

i) Multiplication of two charges.

ii)Inverse square of the distance. 

Elaborating coloulmbs second law. 

 

Consider two charges Q1 and Q2. 

 

ie, F ∝Q1*Q2      ----------＞second law (i).

F∝1/d^2 ---------------≻second law(ii).

F∝ Q1Q2/d^2

F=k. Q1Q2 /d^2

 

K  is constant,so its value is 

 

 1➗4ㄫεoεr

εo=absolute permittivity of vaccum or air

=8.854*10^-12 farad/meter

     

 

εr=relative permittivity of the medium.

 (value is 1 for air or vaccum medi)

 

F=q1q2 ➗(4πεoεr)

         

F= q1q2 ➗(4π*8.854*10^-12*εr*d^2)

while elaborating the condition,we get

 

F=(9*10^9*Q1Q2)/(d2)

 

Problem-1

 

   A charge of 10micro coloumb is placed 100cm away from a charge of 50 micro coloumb in a medium of relative permittivity,4.5.Calculate the force between them.

solution .

Q1=10 uc =10*10^-6 c

Q2=50uc  =10*10^-6 c

d=100cm  =100*10^-2 m

                    εr=4.5

F= q1q2 ➗(4π*8.854*10^-12*εr*d^2)

 

=(10*10^-6*10*10^-6)➗( 4π8.854*10^-12*4.5                                             (100*10^-2)^2)

                  

F= 1N