Spectroscopy Demonstrations
Activity:
Students are given spectroscopes or gratings and shown various emission
spectra
Science Standards:
Nature of Science, Energy & Matter, and Scientific Models (Conceptual)
Objectives:
The student will observe that electrically charged, rarefied gas emits
photons.
The student will observe the light can be separated into a spectrum.
The student will identify the composition of gases using a spectrum chart.
Materials:
Various vacuum gas spectral tubes
spectral tube power supplies
student spectroscopes or gratings
emission spectrum charts
Introduction:
The only information that astronomers receive from the stars is that
light that we passively receive. This light carries an enormous amount
of information regarding the star's temperature, composition, magnetic
fields, and motion. This information is decoded by splitting the light
into a spectrum using a spectroscope. As electrons change energy levels,
the emit (or absorb) photons of particular and predictable frequencies.
The bright line spectrum that results is often called an emission spectrum
or a characteristic spectrum. Every atom has an individual and characteristic
spectrum, much like every student has a personal fingerprint, that is identifiable.
Directions:
1. Demonstrate a hydrogen spectrum, note the colors and positions of
lines.
2. Demonstrate a helium spectrum, it is more complex because of more
electrons.
3. Demonstrate other rarefied gases and identify using a spectral chart.