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Reflectance Spectroscopy Lab
Different colors correspond to different wavelengths of visible light
665 nm
630 nm
600 nm
550 nm
470 nm
425 nm
400 nm
Today’s Lab• If we shine light on an object, some light is
absorbed and some is reflected
• Which wavelengths/colors are absorbed versus reflected?
Incoming white light
(all colors)
White paper
Incoming white light
(all colors)
White paper
White paper reflects all
wavelengths
Incoming white light
(all colors)
Black Paper
Incoming white light
(all colors)
Absorbs all wavelengths
Green PaperReflects green
light
Incoming white light
(all colors)
Absorbs other colors
Objects appear to be different colors because of the light they reflect
Reflected light versus emitted light
Reflected light versus emitted light
Reflected light versus emitted lightToday’s Lab
Spectrum: a plot that shows how reflected light from an object varies with wavelength
Spectrum: a plot that shows how reflected light from an object varies with wavelength
Different objects have unique spectra
Reflectance Spectrometer
Shines a single wavelength of light on an object and measures intensity of reflected light
Reflectance Spectrometer
Has 2 infrared channels
Infrared light has longer wavelength than red light
Can think of infrared energy as the heat an object emits• Humans emit infrared energy• Planets emit infrared energy