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