• The concept of refraction and internal reflection
• The index of refraction
• The "critical angle"
• How prisms work
• How a rainbow forms
• The behavior of a converging and diverging lens
• The "three key rays"
• How a pinhole lens produces an image

Directions: Check out the links within each titled section, then answer the questions. More importantly, understand the answers to each question. (Let me know if there are any links that do not work.)

• Refraction and Internal Reflection - Click blue part of the flashlight twice to see angles.
• The Physics of a Rainbow (Simple)
• The Physics of a Rainbow (Complex)
• The Complexities of a Prism
• A Fish's Point of View

1) Explain, using diagrams, and labelling which substance has the higher and lower refractive index, the following:
   a) Refraction from a substance with a low refractive index into a substance with a higher index.
   b) Refraction from a substance with a high refractive index into a substance with a lower index.
   c) The "critical angle".
   d) Internal reflection.

2) Explain how a "simple" rainbow is formed. Be sure to show where you, the sun, the rain drops (rainbow) would have to be in relation to one another.

3) How does a prism work, and what is dispersion?

4) Explain how a fish can look up at the surface and still see the horizon.

Snell's Law

• Snell's Law

1) Explain how this deepened your understanding of Snell's Law.

Lenses

• Object/Image Relationship and the Three Key Rays
• Object/Image Relationship in a convex (converging) lens.
• Object/Image Relationship in a concave (diverging) lens.
• Converging Lens and 5 Non-Key Rays
• Diverging Lens and 5 Non-Key Rays
• Object/Image Relationship in both lenses and mirrors!
• Thickness of a Convex Lens

1) Explain what happens to the image, as an object starts very far away from a converging lens, and moves towards the lens until the object is right up against the lens.

2) Explain what happens to the image, as an object starts very far away from a diverging lens, and moves towards the lens until the object is right up against the lens.

Pinhole Optics

• The World Through a Hole

1) Explain how a pinhole camera would work.