Teachers' Notes - Chemical photography: seeing in a different light

Infrared in a shoebox

See students' sheet for full instructions on how to set this up. This procedure has been modified from an experiment on http://coolcosmos.ipac.caltech.edu/ (NASA/JPL-Caltech), which also has other useful information on infrared spectroscopy.

This experiment can be done in groups of two or four, depending on the class size. You may want to save time by pre-cutting the boxes (this has been left in the student procedure as you may like to ask them to do this) and painting and taping the thermometers before the lesson.

The temperatures of the colours should increase from the blue to red part of the spectrum. The highest temperature should be just beyond the red part of the visible spectrum. This is the infrared region. You can discuss these other forms of light as an extension to the experiment.

You can also get the students to measure the temperature of other areas of the spectrum, e.g. the area just beyond the blue. You can also try the experiment at different times of the day.

For more information about Chemical Photography visit www.imperial.ac.uk/vsci or download the exhibit team's information sheet here.

Materials required

Glass prism - don't use plastic prisms as they don't work as well
Alcohol thermometers - three per group
Permanent black marker or black paint
Scissors or a prism stand
Cardboard box
Blank sheet of white paper

Safety: Wear safety glasses. A risk assessment must be done for this activity.

Discussion

(relates to the What's next section of the students' sheet)

The bulbs of the thermometers are blackened to absorb heat more efficiently and the temperatures of the colours should increase from the blue to red part of the spectrum.

The highest temperature should be just beyond the red portion of the visible light spectrum which is the infrared section.

Ultraviolet light, X Rays and radio waves are all invisible parts of the spectrum. You can extend the activity by measuring the temperature of ultraviolet light.

Curriculum links

Chemical and material behaviour.

• 6d: The properties of a material determine its uses

Energy, electricity and radiations

• 7c: Radiations, including ionising radiations, can transfer energy
• 7d: Radiations in the form of waves can be used for communication

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