In
physics, an
inverse-square law is any
physical law stating that a specified physical
quantity or intensity is
inversely proportional to the
square of the
distance from the source of that physical quantity. The fundamental cause for this can be understood as geometric dilution corresponding to point-source radiation into three-dimensional space (see diagram). Mathematically formulated:
It can also be mathematically expressed as:
The divergence of a
vector field which is the resultant of radial inverse-square law fields with respect to one or more sources is everywhere proportional to the strength of the local sources, and hence zero outside sources.
Newton's law of universal gravitation follows an inverse-square law, as do the effects of
electric,
magnetic,
light,
sound, and
radiation phenomena.