Optics Exploration

Purpose

Simple materials will be used to better understand optics, including reflection, refraction, and total internal refraction.

Problems

This exploration will include 3 activities to investigate the following:

1. How does a camera obscura invert an image?
2. Why does a fishbowl or other curved, clear substances, distort images?
3. What makes light stay within a stream of water and not leave to the surrounding air?

Part 1: Camera Obscura

Experimental

Go to the Pringles Pinhole Camera Website and follow the directions there.

Observations and Discussion

1. Describe or and draw what you saw when looking through your camera obscura.
2. Why would you not see an upside down image of what is outside on a wall opposite of a window?
3. With the help of your teacher, and what you know about light, explain why the image appeared as it did.

Part 2: Total Internal Reflection

Materials

• empty 2-L bottle
• pushpin
• tape
• water
• bucket or sink        
• laser

Procedure

1. Using the pushpin, poke a large hole (push the pin through the bottle 2-3 times) in side of the empty bottle about 4 inches from the bottom. Cover the hole with a piece of tape.
2. Fill the bottle about half full of water.
3. Set the bottle upright on a table or countertop so that when the water comes out of the hole it goes into a bucket or sink. Remove the tape covering the pinhole.
4. Shine a laser through the bottle so that it exits through the hole with the stream of water.

Observations and Discussion

1. Describe what happened to the laser as it went through the bottle.
2. Explain why this happened.
3. Would we see the same results if we shined the laser from air to the stream of water? Try it and explain your results.

Part 3: Fishbowl Lens

Materials

• curved fishbowl
• newspaper
• magnifying glass

Procedure

1. Place a piece of newspaper or other paper with print behind a fishbowl with water in it.
2. Compare how the print looks through the air and through the fishbowl. Move the paper so it is close to the fishbowl and further from the fish bowl. Note any changes.

Observations and Discussion

1. How did the print compare when it was being viewed through the air and directly behind the fishbowl?
2. What happened when you moved the print further back from the fishbowl?
3. Your teacher has a magnifying glass for you, which makes the print larger as did the fishbowl. Describe the shape of the magnifying glass when looking at it from the side. What kind of lens is the magnifying glass?