Coulomb’s law can be applied to any point charges. It is given by:
Since , it follows that, for a point charge, the electric field strength is given by:
Gravitational and electric fields show some similarities and differences:
|Force is between
|Objects with mass
|Objects with charge
|Constant of proportionality
Applies to all materials
|ε depends on the medium in which the field exists
|Field strength in a radial field
|Nkg-1 or ms-2
|NC-1 or Vm-1
|Definition of Field Strength
|Force per unit mass
|Force per unit charge
|Force in a radial field
|Can be attractive or repulsive
|Potential in a radial field
Always less than zero.
Sign depends on charges
|Definition of Potential
|Work done in bringing a unit mass from infinity to the point in the field.
|Work done in bringing a unit positive charge from infinity to the point in the field.
|Ep = Fm