Task 2: Pinhole investigation of light and lenses Prediction: What would happen to the image on the screen if you were to take away the lens altogether? Now try it. (Leave the screen Where it is and mark the position of the lens for future tasks.) Is there still an image on the screen? Is there light on the screen? About light / Here is a picture of the light bulb. Draw lines ___ showing some of the paths that light rays take after being created at the circled region on the lament. Draw only rays that come from the region. Now, draw lines showing some paths that light rays take after being generated all over the hot lament. Make your drawing represent as many different possibilities as you can without losing legibility. Pinhole patterns Prediction: What will you see if you put a card with a small hole in it between the bulb and a piece of paper as a screen? Use a pencil to punch a small hole in a note card and put the card about halfway between the light source and the screen so that the pencil hole is about 30cm from the bulb. Examine the pattern formed on the screen. What do you see? Is the pattern upside down or right side up with respect to the lament itself? Is it ipped right to left? (You can tell by holding a pencil in mm of the bottom part of the bulb and seeing where it appears on the screen.) How is the pinhole pattern different from an image produced by a lens? To help explain what is happening with the pinhole, draw rays coming from different parts of the lament. Show some that make it through the hole to the screen as well as some that are stopped by the card. Card with hole screen Use your diagram to explain how pinhole patterns are formed. Hint: Where does lightom the top parts ofthelament end up? Prediction: What would you see if the card had three holes in it instead of one? Try it. What do you see? Prediction: What will happen to the patterns if you move the screen closer and farther from the holes? Try it. What happens to the patterns? Pinhole pattern and lens Turn off your light, poke more holes in your card and use it to cover up a lens as shown here so that light from the bulb will pass through both the holes and the lens before it strikes the screen. Prediction: What will you see on the screen when the light is turned on? What if the screen is moved closer? What if the screen is moved farther away? if?) \" \"\"- O . O O Q O O , o 0 _ "- O . x\" O O O '1'}!- c. ________ Q. ''''''''' Q35 " Try it. Move the screen closer and farther away. What do you see? What happens when you cover up the holes one at a time? Ifyou poked even more holes in the card, what would you see? Ifthe card had too many holes in it, it wouldn't be there. Use the idea of a collection of holes edge-toedge across the lens to describe what you would see as the screen were moved closer and farther away. What would all the patterns look like when the screen wasn't at the focus position? How do lenses form images