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The Electromagnetic Spectrum
'
Invisible light
'
discovered by
William Herschel in ~1800 using a
thermometer and a prism. Called it
Infrared Radiation
.
Hertz discovered radio waves in 1888 with sparks
Rontgen discovered X-rays in 1895 because his film kept getting ruined
It's all electromagnetic radiation
Wavelength,
l
, can vary over a HUGE range
Visible light only a small portion of the
electromagnetic spectrum
4 x 10
-7
m (
blue
) to 7 x 10
-7
m (
red
)
or
400 to 700
nanometers
(nm)
1 nm = 10
-9
m
Recall energy, frequency and wavelength are all related
Short wavelength radiation specified by energy (high energy)
UV though Infrared refered to by wavelength
Microwaves through radio refered to by frequency (low energy)
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