- Review how refraction and reflection govern the behavior of light at boundaries - Make the connection between prisms and lenses - Discover how lenses of different types interact with light and are used to project images TODAY’S OUTCOMES: BEHAVIOR OF LIGHT

Trish has a large fish tank with 4 fish in it. But when she tries to count them, sometimes she sees more! Use the picture below to explain how Trish can sometimes count the same fish twice (this is a view from above, and the dark lines represent the glass walls of the fish tank). Look back at the example of the object under water, and do it for both walls separately. Let’s do the right wall first. 1) Light travels in a straight line until it hits the wall. 2) Light that strikes the wall perpendicularly just continues in a straight line. 3) Light going from water to air DECREASES in angle with respect to the boundary, and the change is bigger at when the angle is smaller. 4) Extend the transmitted lines - where they intersect is where the image will appear! = image of fish

Trish has a large fish tank with 4 fish in it. But when she tries to count them, sometimes she sees more! Use the picture below to explain how Trish can sometimes count the same fish twice (this is a view from above, and the dark lines represent the glass walls of the fish tank). Look back at the example of the object under water, and do it for both walls separately. Now the other wall 1) Light travels in a straight line until it hits the wall. 2) Light that strikes the wall perpendicularly just continues in a straight line. 3) Light going from water to air DECREASES in angle with respect to the boundary, and the change is bigger at when the angle is smaller. 4) Extend the transmitted lines - where they intersect is where the image will appear! = image of fish

Trish has a large fish tank with 4 fish in it. But when she tries to count them, sometimes she sees more! Use the picture below to explain how Trish can sometimes count the same fish twice (this is a view from above, and the dark lines represent the glass walls of the fish tank). Here, I keep only the light rays that go to Trish. = image of fish When light passes from water to air, the angle a light beam makes with the boundary decreases, as according to the Law of Refraction. Two separate surfaces at different angles form 2 separate images, so Trish sees 2 fish.

round water bottle (top view) screen Light incident on a clear object passes through it, but the light beams refract in different directions, depending on the angle the object’s surface makes with the beam. Thus, the light does not illuminate a surface beyond the bottle in a uniform manner - some areas will be brighter than others. > Explain, what does refraction have to do with clear objects making shadows? right edge of shadow left edge of shadow bright center, darker edges

You can get both REFLECTION and REFRACTION of a light beam simultaneously at a boundary: thick piece of glass at an angle

You can get both REFLECTION and REFRACTION of a light beam simultaneously at a boundary: thin piece of glass at an angle

You can get both REFLECTION and REFRACTION of a light beam simultaneously at a boundary:

Main angles of refraction

Many of you observed that if the light refracts at a sharp enough angle, that different colors of light emerge, instead of a white beam.

- Both reflection and refraction can occur simultaneously at the boundary between materials - How to apply laws of reflection and refraction to light on a flat surface WHAT YOU ARE EXPECTED TO KNOW:

- Review how refraction and reflection govern the behavior of light at boundaries ✓ - Make the connection between prisms and lenses - Discover how lenses of different types interact with light and are used to project images TODAY’S OUTCOMES: BEHAVIOR OF LIGHT

11. In diagram A, below, show what will happen to a laser beam directed towards a wedge made of some material. In diagram B, show what happens to three parallel laser beams. (Hint: Think of Diagram B as two prisms glued to a thick glass square....) focal point

12. In diagram B, the light beams cross somewhere (“the focal point”) after going through the six-sided object. Suppose instead there were a light source at the focal point, emitting light towards the six-sided object. What would happen to these light beams? Show this on the diagram below. (Hint: Think back to Question 9) focal point

13. If we want every parallel beam to go to the same focal point, we need an object with a curved surface (a lens). On this diagram, continue the lines to show how the light beams come together at the focal point. focal point

14. Another way to accomplish this is to use many wedge-shaped pieces (this is called a Fresnel lens (the word is pronounced “fre-NELL”). Draw lines showing how all the light beams come together at the focal point. focal point