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Electric Charges And Fields

Question
CBSEENPH12037259

Write the complete explicit vector form of Coulomb's law.

Solution

Consider two charges q1 and q2. Let the position vectors of the respective charges be r1 and r2.


Let, the force acting on qdue to qbe F12 and the force acting on qdue to qbe F21.

The vector leading from 1 to 2 is denoted by r21 :
                 
 r21rr1 
ly, vector leading from 2 to 1 is denoted by r12:
                   r12=rr2
and
              r12=-r21.

The direction of a vector is specified by a unit vector along the vector. 
              
              r21=-r12

Now, Coulomb's force law between two point charges qand q2 when force is acting on q2 due to q1 is expressed as:

 F21=14πε  q1q2r212 r21

And, force acting on qdue to qcan be expressed as:
 
F12=14πε  q1q2r122 r12
 
 F12 =-F21