When the linear size of charged bodies are much smaller
than the distance separating them, the size may be ignored and the
charged bodies are treated as point charges Coulomb measured the
force between two point charges and found that it varied inversely as
the square of the distance between the charges and was directly
proportional to the product of the magnitude of the two charges and
Rationalised 2023-24
Electric Charges
and Fields
7
acted along the line joining the two charges Thus, if two
point charges q1, q2 are separated by a distance r in vacuum,
the magnitude of the force (F) between them is given by
2
1
2
q
q
F
k
r
=
(1 1)
How did Coulomb arrive at this law from his experiments