Any point source which
spreads its influence equally in all directions without a limit
to its range will obey the inverse square law. A simple
experiment can illustrate this.
This comes from
strictly geometrical considerations. The intensity of the influence
at any given radius r is the source strength divided by the area of
the sphere surface at that radius.
Being strictly
geometric in its origin, the inverse square law applies to many different
phenomena.
Point sources of
gravitational force, electric
field, light, sound or electromagnetic or nuclear
radiation obey the inverse square law.
Inverse
Square Law, Gravity
As
one of the fields which obey the general inverse square law, the gravity
field can be put in the form shown below, showing that the acceleration
of gravity, g, is an expression of the intensity of the gravity field.
Inverse
Square Law, Electric
As
one of the fields which obey the general inverse square law, the electric
field of a point charge can be put in the form shown below where point
charge Q is the source of the field. The electric force in Coulomb's
law follows the inverse square law.
Inverse
Square Law, Radiation
As
one of the fields which obey the general inverse square law, a point
radiation source can be characterised by the relationship below whether
you are talking about becquerels, Roentgens , rads, or rems . All
measures of exposure will drop off by inverse square law.
