The gravitational field strength, EG, at a point is the force per unit mass acting on a body arising from another object's mass. When a force acts on a point m, by definition:
Gravitational field strength
Gravitational field strength has units N kg-1. The magnitude of gravitational field strength can be calculated using Newton's law of gravitation: F = GmM/r2. For a mass m, the gravitational force acting on it equals: mEG. So,
The electric field strength, E, is the force per unit charge a body exerts on another, much smaller, body. When a body of charge Q has a force F acting on it as a result of the field, the gravitational field strength at that point is defined as:
The field strength of an electromagnetic wave is usually expressed as the rms value of the electric field, in volts per meter. The field strength of a magnetic field is usually expressed in ampere-turns per meter or in oersteds. Synonym radio field intensity.
Electric field strength
The electric field strength at a distance r can be calculated using .
So,
Where e represents permittivity and e0 permittivity of a free space.