Suppose that a laser beam is submerged in a tank of water (don't do this at home) and pointed upwards towards water-air boundary. To understand total internal reflection, we will begin with a thought experiment. Total internal reflection, or TIR as it is intimately called, is the reflection of the total amount of incident light at the boundary between two media. The phenomenon observed in this part of the lab is known as total internal reflection. What happened? Why did light not refract through the second face? Then finally, to their amazement, they looked through the third face of the block and clearly see the ray. This discrepant event bothers many as they spend several minutes looking for the light to refract through the second boundary. Now instead of transmitting across this boundary, all of the light seems to reflect off the boundary and transmit out the opposite face of the isosceles triangle. The ray of light then travels in a straight line through the glass until it reaches the second boundary. This ray of light passes across the boundary without refraction since it was incident along the normal (recall the If I Were An Archer Fish page). A ray of light entered the face of the triangular block at a right angle to the boundary. The diagram on the left below depicts the physical situation. When done so, an unusual observation - a discrepant event - is observed. A common Physics lab is to sight through the long side of an isosceles triangle at a pin or other object held behind the opposite face.
0 kommentar(er)
