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A Comparison of Electric and Gravitational Fields
| Gravitational Field | Electric Field | |
|---|---|---|
| Force is between | Objects with mass | Objects with charge |
| Constant of proportionality | G 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 Vector |
 NC-1 or Vm-1 Vector |
| Definition of Field Strength | Force per unit mass | Force per unit charge |
| Force in a radial field |  Always attractive Vector |
 Can be attractive or repulsive Vector |
| Potential in a radial field | 
Jkg-1 Scalar Always less than zero. |
JC-1 Scalar 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. |
| Potential Energy | Ep = Fm | W=VQ |