Electrical Potential from Point Charges

In mechanics we considered F=Gm1m2/r**2 for the force between two masses and from this developed the formula for gravitational potential energy between point masses as EP= - Gm1m2/r

Similarly if we consider F=kq1q2/r**2 we can develop the equation for the electrical potential energy between point charges as EEP=kq1q2/r

Recall by definition V=EEP/q

We can get

V=kq/r

or

V=(1/4peo)q/r

Symbol
Description
Units
V
the electrical potential
V (Volts)
k

The Coulomb constant

8.99 x 10**9
Nm**2C**-2
eo

Permittivity of Free Space

8.85 10**-12

(not to be confused with permeability of free space which applies to magnetism)
C**2N**-1m**-2
q
electric charge
C
r
distance from the centre of the point charge
m

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