Saturday, April 24, 2010

Rod Refraction

The rod pictured is not physically bent, but it appears to bend because of the physics principal of refraction, which is the distortion of light waves as they move from one medium to another. Refraction can be categorized with the index of refraction, represented by n.

So, how does refraction create the optical illusion of the bent cleaning rod? Well, as explained earlier, refraction occurs when light goes from one medium to another, in this case from air to water. The light goes from a medium in which it moves fast, the air (n=1), to a medium in which it slows down, the water (n=1.33). As the light enters the denser medium with a higher index of refraction it bend towards the normal (the perpendicular line originating from the spot that the pool rod touches the water. However, I have just said that the light ways bend towards that normal and it looks as if the pool rod is bending away from the normal line, how can both the picture and my statements be true? It is because the appearance of the rod is opposite the direction of travel of light going into the water. As the light enters the water the rays bend towards normal but as the ray exits it bends away from the normal and travels toward your eye at a "lower" angle than the angle that it would approach your eye if the light travelled in a straight line.

1 comment:

  1. Very good picture and excellent explanation!