It was the great Scottish physicist James Clerk
Maxwell (1831-1879) who showed that electric and
magnetic fields fluctuating together can form a
propagating wave, appropriately called an
electromagnetic wave. Sunlight is a mixture of
electromagnetic waves having different wavelengths.
Each wavelength in the light produces a different
color sensation in our eyes, from red to green to
violet. The colors are present in the sunlight, in the
sense that sunlight is a mixture of different
wavelengths. When this mixture strikes an object,
different parts of the object reflect certain
wavelengths more strongly than others, giving each
part its color pattern. Thus, the colors of an object
"belong" to the electromagnetic waves that reflect
from it. This chapter examines the general properties
of electromagnetic waves and explores their many uses
in our lives.