Physics Demo Number: 171

Approximate Run Time: 15 min

Various Spectral Tubes of Different Gases

Demo Description

Various spectral tubes containing different gases are paired with power supplies

to run them. Students look at the tubes through hand-held diffraction gratings

to see the spectral lines for each gas.

Scientific Principles

• View Characteristic Atomic Transition Line Emission Spectra for Different Gases with the aid of Diffraction Gratings

Equipment

• 4 Spectral Tube Power Supplies

• Various Spectral Tubes

• Clear line-filament incandescent white light source

• Acetate sheet

• Glass filters

• Replica Diffraction Gratings to pass out to students

Equipment Location

• Two 171 Kits,

  4 Power Supply Boxes

  All on [A-1-4]

-11

1

2

3

Instructions

Note: One should emphasize to students that they MUST hold the replica gratings very CLOSE to their eyes (and LOOK very far to the side ) to see the spectral lines.

The four power supplies are shown with a tube in each, along with a line filament white light bulb and some of the replica diffraction gratings to give the students for viewing the spectra of the various sources.

A closer view of some of the components is afforded by the second photo.

The third photo shows the yellowish acetate sheet draped over one of the tubes to illustrate the idea of absorption lines.

Also seen is a green glass filter and a blue glass filter for absorption of lines from the white light source.

Writeup created by David A. Burba

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