Subject Area(s): Science: Light, Chemistry Activity Title : Engineering with Light Grade Level: 5-8 Time Required: 1 hourGroup Size: Groups of 2Expendable Cost per Group: $2Summary:Engineering ConnectionKeywordsEducational StandardsPre-Requisite KnowledgeLearning ObjectivesAfter this lesson, students should be able to:Materials ListEach group needs:To share with the entire class:Introduction / MotivationVocabulary / DefinitionsProcedureImageInvestigating QuestionsActivity ExtensionsReferenceshttp://www.lawrencehallofscience.orgOwnerContributorsCopyrightDrexel-SDP GK-12 ACTIVITY Subject Area(s): Science: Light, Chemistry Activity Title : Engineering with Light Grade Level: 5-8 Time Required: 1 hour Group Size: Groups of 2 Expendable Cost per Group: $2 Summary: In this activity we’ll try to establish the fundamentals of how light might used as a tool. Engineering Connection All major disciplines of engineering are currently interested in microtechnology. Electrical engineers create microchips. Environmental engineers use the techniques to study bacteria. Chemical engineers study the chemistry behind the reactions and develop the photochemicals of the future. Mechanical engineers create tiny moving devices that are much more efficient than previous designs. KeywordsPhotochemistry Microchips Photosensitive Light spectrum Wavelength Educational Standards • Science: • PA 3.4.7B Know that the sun is a major source of energy that emits wavelengths of visible light, infrared and ultraviolet radiation. • PA 3.2.C Design an investigation with limited variables to investigate a question. Pre-Requisite Knowledge A background in the electromagnetic spectrum may be useful, but not necessary for this lesson. Photosensitive chemicals are responsive to different wavelengths of light, and the idea of how these wavelengths can be produced or filtered may add to the lesson. Learning Objectives After this lesson, students should be able to: • Explain how light may be used as a tool to create patterns. • Discuss how very small patterns may be made with light. • Demonstrate how to use light to transfer a pattern. • Compare their pattern to the patterns that might be imprinted on a CD or DVD. Materials List Each group needs: • One sheet of sunprint paper • One piece of regular paper. To share with the entire class: • Clear plexiglass overlay • Bright light for exposure. A black light or ultraviolet light will work best, but direct sunshine will also suffice. • Water bath large enough to submerge an 8 ½ x 11 sheet of paper. Introduction / Motivation 2Many high-tech processes are dependent upon the use of photochemistry. Optical disks such as CD’s and DVD’s depend on this phenomenon, and the process for making microchips also depends on photochemistry. Photochemistry involves the change of a chemical from one state to another after exposure to light. Vocabulary / Definitions Word Definition Photochemistry The chemistry of the effects of light on chemical systems Spectrum The colored band of light made when white light passes through a prism Wavelength The length of the light wave which determines its color. Develop To expose photographic material in order to bring out the picture Procedure Before the Activity Discuss how information might be encoded using light. We interpret variations of light on a printed page by determining the bright and dark patterns on the paper which represent the letters and words. On a CD, microscopic patterns are used in order to encode information. The method used to imprint the information uses photochemistry. Since the wavelengths of light are so small (400-700 nm), features of a similar scale may be encoded. The fundamental photochemistry for encoding CDs is similar in principle to the technique we’ll use to transfer patterns to Sunprint paper. With the Students 1. Have the students cut out patterns of their own choosing in normal non-photosensitive paper. Theses patterns will later be transferred to the sunprint paper. 2. Cover the Sunprint paper with the cutout patterns. 3. Cover the patterns and Sunprint paper with the Plexiglass sheet. 4. Expose the entire system to ultraviolet light or direct sunlight for the amount of time recommended. 5. After the exposure, develop the Sunprint paper in a water bath. 6. Observe the results. Image 3http://www.lawrencehallofscience.org Investigating Questions 1. What happened to make the change in the Sunprint paper? 2. How small can the patterns be transferred? 3. Why was the water necessary to develop the image? 4. How can this principle be applied to making a CD or DVD? Activity Extensions Students may consider ways to make a code that could be transferred to the Sunprint Paper. They can also consider how a CD or DVD might be encoded. References http://www.lawrencehallofscience.org Owner Drexel University GK-12 Program Contributors Ed Steager Copyright Copyright 2007 Drexel University GK12 Program. Reproduction permission is granted for non-profit educational use 4Version: Mar 2007