ABSTRACT
Light is an electromagnetic radiation, with wave and particle properties. The electromagnetic
radiation has a spectrum or wavelength distribution from short wavelength (1026 nm, gamma
and x-rays) to long wavelength (1015 nm, long radio waves). About 99% of the Sun’s radiation
is in the wavelength region from 300 to 4000 nm and it is called the broadband or total solar radi-
ation. Within this broadband, different forms of energy exist, which can be associated with specific
phenomena such as harmful and potentially mutagen ultraviolet radiation (UV 100-400 nm), sight
(visible light 400-700 nm), and heat (infrared radiation 700-4000 nm) (Figure 5.1). Therefore,
what we see as visible light is only a tiny fraction of the electromagnetic spectrum; detecting the
rest of the spectrum requires an arsenal of scientific instruments ranging from radio receivers to
scintillation counters.
