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

EE=kq1q2/r

note for this equation - EE is zero at infinity. EE is always negative for attraction forces (just as it is for gravitational forces) however EE is positive for repelling forces.

[ graph would be good here see fig 2 p350 gr 12 text ]

Recall by definition V=EE/q

We can get

V=kq/r

Symbol	Description	Units
V	the electrical potential	V (Volts)
k	The Coulomb constant 8.99 x 10**9	Nm**2C**-2
q	electric charge	C
r	distance from the centre of the point charge	m

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