Properties of Infrared Light

Absorption, Reflection, Refraction

Aims:

· Bring various sorts of objects between your remote control and the IR-sensor and look at the changes of the signal’s amplitude. Rank the objects according to their ability to absorb infrared light. Among the materials there should be a glass tub filled with water and a glass plate. It could be interesting to test how many sheets of paper are needed to stop the signal totally.

· Put the remote control directly in front of the IR-sensor (distance about 40 cm) and evaluate the amplitude. After that, adjust the remote control at right angles to the normal direction (as shown in the picture) and measure the amplitude again using different reflectors (metal plate, glass plate, mirror, book, etc.). Which reflector is best? What is the best angle for reflection? Why?

· We have already seen now that infrared light has more or less the same properties as visible light. Let’s test whether or not infrared light can be refracted. We put the remote control in front of the IR-sensor at a distance of about 1 m. We use a convex lens (f = 15 cm) and try to focus the IR-radiation. Result?

List of Materials:

· one oscilloscope

· one remote control

· one IR-sensor

· one glass tub filled with water

(about 6 cm thick)

· one glass plate

· one mirror with holder

· one convex lens (f = 15 cm)