Making Sense of Spectra

This Spectrum Tool will help you connect the visual color display of a light source's spectrum—like the color image you see in a spectroscope—with a graph of the light’s spectrum.

Measure Wavelengths and Energy

Spectrum Tool.

  1. Move the measuring tool across the spectrum graph with your cursor to identify the wavelengths (in microns) of the three brightest features (labeled A, B, and C) in this spectrum.
  2. Use the unit dropdown menu to change the unit of the measuring tool to nanometers and remeasure the wavelengths. Repeat for Ångstroms and electron volts (a unit of energy).
  3. Use the measuring tool to estimate the brightness of the three brightest features. (You can use your pencil or a ruler to help eyeball the brightness level on the y-axis.)

Spectrum Notebook.

  1. As you measure the features in the tool, write the values in your table, one column at a time.
  2. Use your completed table to answer the questions.
Source:
Lamps — Fluorescent Bulb
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
A
B
C
Bottom axis ticks
Wavelength (Microns)

Use this dropdown menu to change the units of the x-axis and measuring tool.

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