Physics Home > Teaching Labs > Astronomy > Emission Spectrum

Topics

Points of Emphasis

Prerequisites

Lab Activities

This lab has two parts:

In Part I, the students measure the wavelengths of the alpha, beta, and gamma emission lines of hydrogen with an optical spectrometer. Using those wavelengths, the energy of the photons producing those lines are computed and compared to the photon energies as predicted by the Bohr theory for the hydrogen atom. Results tend to be within 1% of the accepted values.

In Part II, the students measure the wavelengths of three emission lines of an unknown gas using the same equipment and techniques as in Part I. The students are asked to compare the spectrum of the unknown gas with that of hydrogen. The students then use a Java applet installed on the computers in the Astronomy lab to identify the unknown gas. [The Java applet consists of a period table. When the used clicks on a specific element, the applet displays the emission spectrum of that element.]

Course Level

Introductory

Student Handouts

Equipment

Number of set-ups available: 5 Per lab station: 1 spectrometer/diffraction grating 1 hydrogen spectrum tube 1 spectrum tube power supply 1 flashlight 1 Handbook of Chemistry and Physics 1 cross hair illuminator 1 small lamp 1 spectrometer stand 1 eye patch 1 box of spectrum tubes for other gases

Notes

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