This picture was taken in a physics classroom with all the lights turned off. A digital camera was used to take this picture. It was taken from a distance of one meter from the projection screen, without zooming in and without the use of a flash. A Hard-Seal Helium Neon laser was used. A projection screen was placed about one meter away from the laser beam source. A cylindrical plastic tube, with a diameter of 4 cm was placed at an angle in front of the laser. The laser beam can be seen on the top of the plastic cylinder. Since the angle of incidence is greater than the critical angle, total internal reflection occurs. This traps the laser beam inside of the cylinder. The same process repeats itself until the laser beam reaches the end of the cylinder. We can see a spiral on the cylinder because of the total internal reflection. This is also projected onto the projection screen. The bright areas on the projection are present, because some light escaped from the plastic tube. The beam is refracted as it passes through the plastic tube, and therefore, it appears different on the projection screen.

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Talha Qureshi & Sarvatit Bhatt
Emery Collegiate Institute, North York, Ontario
1st Prize ( High School Class Project Category )

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