The passive Infrared motion sensor functions in the
electromagnetic spectrum just as other sensors, but its core
attributes is exhibited at a wavelength that is longer than
visible light. Thus as human body whose radiation is
strongest at a wavelength of 9.4um implies that it any
external sources will not pass through many as a result the
present on human within the infrared can be coded and
reported. Thus the sensor output follows very closely the
photometry inverse square law [10].