Laboratory Exercise 2
In this laboratory exercise students will examine the spectrum of various
light sources and the action of various filters using spectral glasses and an
Ocean Optics Red Tide Spectrometer. They will identify the atoms or
molecules of an unlabeled hot gas using the measured emission spectrum.
The spectrometer:
The Ocean Optics Red Tide Spectrometer uses a diffraction grating to deflect
light with different wavelengths through different angles. Light enters a fiber
optic probe through a tiny hole at one end. It travels down the fiber optic
cable into the spectrometer. The grating deflects light with different
wavelengths onto different positions of a position-sensitive detector. The
output of the detector is passed to a computer via a USB cable. The Ocean
Optics SpectraSuite software provides real-time readout of the measured
spectrum on the computer screen.
Equipment:
Incandescent lamp
Mercury Lamp
Gas Discharge Lamp
Laser
LEDs
Filters
Spectral Glasses
Procedure:
Look at each light source through the spectral glasses and measure its
spectrum with the spectrometer. Make notes of your observations.
Examine the spectrum of the incandescent light source with and
without filters.
What wavelength range does this spectrum cover?
What wavelength range is absorbed by the yellow filter?
What wavelength range is absorbed by the green filter?
What wavelength range is absorbed by the "pink" goggles?
They protect your eyes from which type of laser light?
What wavelength range is absorbed by the "blue-green"
goggles?
They protect your eyes from which type of laser light?
Examine the spectrum of the Mercury Lamp.
What are the wavelengths of the three most prominent
lines?
If you click on a line the software displays the wavelength
in nanometer (nm) in a box.
Approximately how wide are those lines?
Point the fiber optics probe towards the room lights. Do
you observe discrete lines on top of the continuous
spectrum? Can you identify the source of those lines?
Examine the spectrum of the gas discharge lamp with the
hydrogen tube.
What are the wavelengths of the three prominent lines?
Examine the spectrum of the gas discharge lamp with the tube
containing an unlabeled gas.
What are the wavelengths of some of the most prominent
lines? Can you identify the gas using the attached tables?
Examine the spectrum of the laser.
What is the wavelength of this laser? What is the
approximate width of the line?
Examine the spectra of the four LEDs. (The longer leg has to be
connected to the positive side (red wire) of the power supply.)
Describe these spectra?
Laboratory 2 Report:
Name:
E-mail address:
In a few words, describe the experiment.
Comment on the procedure. Did you encounter difficulties or
surprises?
Present your observations.