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Purpose:
The purpose of this activity is to have the students repeat Herschel's experiment to prove the existence of infrared radiation.
Materials: (per group)
- prism
- lamp or sunlight
- three thermometers
- lab hand-out
- pen or pencil
About this Activity
This activity involves a laboratory investigation for students to perform. In this investigation students will be determining the existence of infrared radiation through Herschel's experiment.
Procedure:
- Discuss what makes up visible light.
- As a review use a prism to show the colors that make up the visible spectrum. (See Activity 2: The Electromagnetic Spectrum) Discuss the wavelengths in relation to their colors.
- Divide students in groups of four.
- Pass out lab hand-out and have the materials ready at their lab tables.
- Give the directions for the lab. You may want to give more guidance to lower grade levels and certain abilities of students.
- Have students begin the laboratory activity.
- After the lab, explain that visible light rays and infrared rays are generally transmitted through the Earth's atmosphere. These are the wavelengths that are regions of high transmittance, called "atmospheric windows," in which are the areas where remote sensing data can be acquired. Discuss the concept of remote sensing.
- As a review from the lab, ask students to describe the relationship they found between infrared radiation and visible light.
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:
- 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.
- 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.
- You should be looking at the various colors.
- Place the first thermometer in the violet range of the spectrum.
- Place the second thermometer in the green range or center area of the spectrum.
- Place the third thermometer just barely beyond the red range of the spectrum.
- After each of the thermometers are placed in their positions, leave them in their positions for at least five minutes.
- Now record the temperatures in the chart below.
Data Chart of Temperatures
| Thermometer Position |
Temperature Before |
Temperature After |
|---|
______________________________________________________________
1) violet
______________________________________________________________
2) green
______________________________________________________________
3) red
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Conclusion Questions:
- Describe the relationship you noticed concerning the temperatures.
- Describe what happened to the temperature of the thermometer that was beyond the red end of the spectrum.
- From the laboratory investigation, what do you think exists beyond the red end of the spectrum? Explain your reasoning.
