Week 15 - Explanations, Inventions & Investigations About Light and Vision

Lesson 4

Lesson 4: Transparent Objects can Refract Light

Science In Action

Read pages 200 - 203

Have you ever been playing in a swimming pool and seen something on the bottom while you were sitting on the edge? But when you went under water to retrieve it, it was in a different place. If this has happened to you then you were the victim of refraction. When light enters a medium (material) like water it slows down a bit. If it enters at an angle to the surface of the water this change in speed causes causes the ray of light to bend away from its original path. This is called refraction.

Fly fishermen often try to cast to a fish they can see underwater. After reading about refraction, where would you cast your line?

Traveling at the Speed of Light!

The change in speed of the light beam is dependent on the density of the material it is passing through. Therefore the amount of bending of the beam from its original course is depends on the density of the transparent material. Scientists have measured each of these materials and given each a 'refraction index' or a measure of the amount of bending for each material.

The Science Behind Refraction

Examine the diagram below, you should be able to label this diagram from memory.

Exercise 1.4: Studying Refraction