Name________________________________ Date______________

Laboratory Investigation on Visible Light and Infrared Radiation

Purpose:

To demonstrate that infrared radiation exists, this experiment will duplicate William Herschel's experiment.

Materials:

(per group) prism, lamp or sunlight, three thermometers, pen or pencil

Procedure:

  1. Place the three thermometers on the lab table where you will be performing the experiment. Allow approximately five minutes to measure the temperature of the air where the experiment will be done. Record the starting temperatures in the chart below.

  2. Using the lamp or the sunlight, create a spectrum that will be projected on the table. You might have to use books to position the prism above the table to get the proper spectrum.

  3. You should be looking at the various colors.

  4. Place the first thermometer in the violet range of the spectrum.

  5. Place the second thermometer in the green range or center area of the spectrum.

  6. Place the third thermometer just barely beyond the red range of the spectrum.

  7. After each of the thermometers are placed in their positions, leave them in their positions for at least five minutes.

  8. Now record the temperatures in the chart below.

Data Chart of Temperatures

Thermometer
Position		 Temperature
Before		 Temperature
After
1.   violet    
2.   green    
3.   red    

Conclusion Questions:

  1. Describe the relationship you noticed concerning the temperatures .

  2. Describe what happened to the temperature of the thermometer that was beyond the red end of the spectrum.

  3. From the laboratory investigation, what do you think exists beyond the red end of the spectrum? Explain your reasoning.

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[LMGFP home page] Contact Karen Krupinsky (kgurley@gsfc.nasa.gov) or
Tammy Seergae (tseergae@umd.edu) for further information.