Reflectance Spectroscopy Lab Different colors correspond to different

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)

Incoming white light (all colors) White paper

Incoming white light (all colors) White paper reflects all wavelengths White paper

Incoming white light (all colors) Black Paper Absorbs all wavelengths

Incoming white light (all colors) Green Paper Reflects green light 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 light Today’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