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3. Wavelength is Color Blue Light: l = 450 nm (nanometers)
Yellow light: l = 550 nm
Green light: l = 600 nm
Red light: l = 700 nm
4. Spectroscopy
5. Spectroscopy Continuum -- Rainbow
Absorption -- Dark Lines
Emission -- Bright Lines
7. But What Causes Spectral Lines? An absorption line (dark line) represents light that has been removed from the spectrum at one particular wavelength
An emission line (bright lines ) represents light that was added to the light of the star
8. Atoms Every atom consist of a nucleus plus electrons, which can be in different energy states
The Bohr Model of the atom imagines the electrons in orbits
When an electron jumps from one orbit
to another it gives of energy, its energy changes.
If it is moving to a lower orbit it emits a photon of light
If it is moving to a higher orbit it absorbs a photon
12. If light from a source passes through a gas cloud, some of it will be absorbed, producing an absorption spectrum
If light comes from a hot gas cloud, it will produce an emission spectrum
If light comes to us directly, it will produce a continuum spectrum What Causes Spectral Lines?