Changes

==Modern meaning in the physical sciences==

==Modern meaning in the physical sciences==

[[Image:Light dispersion conceptual.gif|right|frame|<center>dispersion of light</center>]]

[[Image:Light dispersion conceptual.gif|right|frame|<center>dispersion of [[light]]</center>]]

In the 17th century the word ''spectrum'' was introduced into [[optics]], referring to the range of colors observed when white light was dispersed through a prism. Soon the term referred to a plot of light intensity or power as a function of [[frequency]] or [[wavelength]], also known as a [[spectral density]].

In the 17th century the word ''spectrum'' was introduced into [[optics]], referring to the range of colors observed when white light was dispersed through a prism. Soon the term referred to a plot of light intensity or power as a function of [[frequency]] or [[wavelength]], also known as a [[spectral density]].