Engaging questions:
- Do you know what types of waves can you not see? How can you prove their existence?
- How do we know, that there is UV radiation?
- How do the sunglasses and sun creams work?
Equipment:
- box (e.g. shoe box),
- prism,
- light-sensitive blueprint paper, (a description of the paper preparation is the Activity III-5)
- Pencil.
Description of the Activity :
Students make an incision in the box and they place there the prism. Then, the box is placed in the sun. The sunlight should be split into different colours of light when it passes through the prism – on the bottom of the box, the white light spectrum should be seen (Figure II.5). In the place where the spectrum is visible, students place the blueprint paper and copy the spectra contour plot (marking the red and blue colour) as soon as possible. The Activity is left for the light exposure for about 20 minutes.
NOTE: The Activity should be performed during a sunny day. In case of poor insolation, the effect may be difficult to observe or may occur after a long time.
Figure II.5. A scheme of the experimental setup.
Discussion:
- Why is the paper exposed in a larger area than the copied contour?
- From the side of which colour is the exposure outside the contour bigger?
- Why does the ozone hole carry an increased risk of sunburns and its consequences?
- Should we cover our eyes with special eye protection if the light of lamps does not dazzle us through the closed eyelids?
- What should the parameters of sunglasses be to effectively protect our eyes?
Experiment developed by: http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities... 2.html