7B11.15 - Spectral Lines/Spectroscopy - Sodium Absorption

Code Number:
Demo Title:
Spectral Lines/Spectroscopy - Sodium Absorption
Spectra of Various Gases, Spectral Lines of Elements
Area of Study:
Optics, Astronomy
Slide Projector, Sodium Absorption Apparatus, (Variable Slit and Lens Unit, Fischer Burner Unit), Grill Lighter, Plexiglas Stand for Slide Projector, Diffusing Screen if desired, and Rock Salt.

See also 7B11.15 in Astronomy.

Video Credit:  Jonathan M. Sullivan-Wood.

The sodium absorption stuff is set up as shown.  Observe the distances fairly carefully as it is a critical part of making this work.  The lens of the slide projector will need to be turned almost clear out.  Light the burners and wait until they burn with a bright yellow flame before putting into the light path.  Focus the camera onto the red-yellow end of the spectrum showing on the grating.

Note: The burners must be lined up in the light path.

The white light spectrum observed will have many streaks in it due to light bulb configurations.  To minimize this the use of a diffusing screen is advised.  The one that we are using is in a 35 mm slide holder and can be inserted directly into the slide projector.

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