SNC2D/2P Summative Light and Optics 15% of your final mark

Transcription

1 SNC2D/2P Summative Light and Optics 15% of your final mark As a group of four, you will work together to make two different types of solar ovens (you will be changing the shape of the reflective surface). You will test your solar ovens and answer analysis. Introduction: The Sun continuously provides Earth with tremendous amounts of solar energy, most of which comes in the form of visible light. Sunlight, when transformed into usable heat, can be a practical source of energy for everyday jobs such as cooking food, heating water, or warming houses. A solar cooker is an insulated box that traps the heat of the Sun for cooking food. The most efficient way to transform sunlight into heat is to shine lots of sunlight onto a dark surface. When light energy (also called radiant energy) is absorbed by an object, it is changed to heat energy. Darker objects absorb more and reflect fewer of the visible light waves that hit them than lighter objects do. It follows that while dull black objects readily absorb more light, shiny silver ones reflect more. Mirrors or other reflective materials including aluminum foil, then, can catch more light and redirect it to the cooking surface, where the energy in the light can be used. The direct and redirected sunlight is converted to heat. Some of the energy heats the air. By using a plastic or glass cover that allows light in but prevents heat from escaping, the energy that arrives as radiation can be used to cook food -- such as the "s'more" featured in the ZOOM segment -- much like a convection oven cooks things by circulating hot air through the cooking chamber. Schedule: Monday, June 13 th Build the solar ovens in class Tuesday, June 14 th Test solar ovens at Windsor park Wednesday, June 15 th Analysis in class

2 Materials: Cone Solar Oven: 2 large sheets of black poster board aluminum foil black construction paper cardboard box Pizza Box Solar Oven: pizza box newspaper aluminum foil black construction paper scissors plastic wrap tape book Also: Ziploc bags graham crackers marshmallows chocolate bar 3 thermometers Methods: Cone Oven 1. To make the Cone Solar Oven, glue two pieces of black poster board together to make one long piece. Cover one side with aluminum foil. 2. Bend the poster board, foil side in, into a cone shape and tape it together. The cone should still be open on both ends. 3. Put black construction paper in the bottom of a cardboard box. This dark surface will absorb heat into the bottom of the box. 4. Prop the cone in the box with the narrower opening pointing down. 5. Put a graham cracker with a marshmallow on top of it in a Ziploc baggie. Chocolate melts faster than marshmallows, so it works best to cook the marshmallow first and add the chocolate later. 6. Put the baggie on the bottom of the box in the center of the cone. Pizza Oven 1. To make the Pizza box Solar Oven, put a few sheets of newspaper in the bottom of a pizza box. Cover the newspaper with black construction paper to absorb heat.

3 2. Cut a flap out of the top of the pizza box two inches from the sides and front but attached in the back. Bend it back and cover the inside of the flap with aluminum foil. 3. Tape plastic wrap across the hole left by the flap. 4. Put a graham cracker with a marshmallow on it on top of the black paper in the bottom of the box. Close the box. 5. Use a book or tape to prop open the flap so that the aluminum foil can catch the sunlight and reflect it onto the marshmallow. Testing your Ovens 1. Make an extra s'more to be the control. Don't put this one in a Solar Cooker. If the control s'more cooks as well as the ones in the Solar Ovens, you will know that the Solar Ovens aren't working better than the sun by itself. Predict how long you think it will take to cook the s'more and which cooker will get hotter and cook faster. 2. You need the sun to make your Solar Ovens work, so you'll need to do your cooking outside. 3. Once you set up your Solar Cookers outside, put a thermometer inside each one and one on the control s'more. This will help you compare the temperature in the Solar Oven to the temperature outside. If the Solar Ovens are working, it will be hotter inside the cookers than it is outside on the control. 4. Check your Solar Ovens every 15 minutes to make sure they aren't in the shade. If the sun moves, move the Ovens so they stay in the sun. 5. Time how long it takes to cook the s'mores. Which oven got hotter? Which one baked more quickly? Why do you think it was faster? When your marshmallows are almost done, add the chocolate to the s'mores, wait a minute for it to get soft, and enjoy a tasty treat!

4 Table of Results for Comparing Solar Ovens: Method of Heating Cone solar oven 15min 30min 45min 60min Pizza Box solar oven Control (no oven) Planning and Analysis Questions: 1. Write a testable question and hypothesis for this lab. 2. What are the independent and the dependent variables? 3. Explain why we used black paper on the bottom of the ovens?

5 4. Explain how the 2 different solar ovens work. Use ray diagrams in your explanation, talk about the type of mirror (aluminum foil part) you used in each. Ray Diagrams: Cone Solar Oven Pizza Solar Oven 5. Which oven cooked faster? Explain why you think it cooked faster.

6 6. What did the plastic wrap or plastic baggie do?

7 Categories Knowledge and Understanding -use appropriate terminology related to light and optics, Constructing a Solar Cooker Level 1 (50-59%) limited of terminology Level 2 (60-69%) some of terminology Level 3 (70-79%) considerable of terminology Level 4 (80-100%) thorough of terminology Application -construction of solar cooker that uses mirrors (aluminum foil) Communication -expression and organization of ideas and information (e.g., clear expression, logical organization) in reflective writing -constructs an optical device with limited organizes ideas and information with limited -constructs an optical device with some organizes ideas and information with some -constructs an optical device with considerable organizes ideas and information with considerable -constructs an optical device with a high degree of organizes ideas and information with a high degree of Thinking -Testable Question, Variables, Hypothesis Thinking -analysis -shows limited of the cause and effect relationship -independent and dependent variables are not measurable - hypothesis is vague and shows no prediction -provides limited answers to analysis -shows some of the cause and effect relationship -independent and dependent variables are qualitative in nature -hypothesis is not written in the if then format but makes a prediction -provides some sufficient answers to analysis -shows a good of the cause and effect relationship -independent and dependent variables are quantitative in nature -hypothesis is written in the if then format and makes a prediction -provides sufficient answers to analysis -shows a thorough of the cause and effect relationship -independent and dependent variables are quantitative and precisely defined -hypothesis is written in the if then format with a well defined prediction -provides rich answers to analysis