Light and Optics

1. Light and Optics Concept Presentation By: Dale Simnett

2. Let’s impress some students! (Using light to transmit information)

3. Overview • Light and Optics concepts • Group activity • Basics & technological applications • Curriculum progression and expectations • Teaching strategies • Misconceptions • How to aid understanding! • Modifications and safety considerations

4. Overview of the Concept • Properties of Light (2 days) • Visible light is an electromagnetic wave that is a part of the Electromagnetic spectrum • White light is comprised of all the colours of the rainbow (ROYGBIV) • Light propagates linearly (travels in straight lines) • Light travels at 3.00x108 m/s • How light interacts with the human eye • Additive colour theory (1 day) • Subtractive colours theory (1 day)

5. Group Activity • Groups of 4 • Discuss the question given to your group • Assign one member to record your groups answer and report. • What property of light does your question relate to?

6. Group Activity • Question # 1: • You have invented a space craft that can travel just faster than the speed of light. You leave Earth in your new craft, travel to the edge of the solar system. Once there, you turn around and set-up a telescope that can see all the to the Earth’s surface. What do you see?

7. Group Activity • Question # 2: • “The easiest way to see into the past is to take a look at the night’s sky.” Explain this statement. OR • If the sun blew up right now, what would you see in the sky?

8. Group Activity • Question # 3: • Our reality is just an illusion of our mind’s interpretation of light. Discuss how this relates to mirages, spear fishing or black holes.

9. Group Activity • Question # 4 • Look across the room and notice someone’s head. Using your hand, pinch the person’s head. How does their head fit in between the much smaller distance between your finger and thumb? • For clarification: • Insert video – KITH Face pincher vs head crusher

10. Group Activity • Question # 5 • How would our vision be different if we could see infrared light? How would security systems have to change?

11. How does the eye work? When light enters your eye, it is focused on your retina. The retina is made of three types of cone cells. First cell responds to red frequencies of light Second cell responds to green frequencies of light Third cell responds to blue frequencies of light When a cell “responds”, it sends a signal to your brain which your brain interprets as colour.

12. Additive Colour Theory • When two or more frequencies of lights reflect off a surface (or enter your eye), more than one cell is activated and your eye perceives the combination of the two colours.

13. Subtractive Colour Theory • In subtractive colour theory, you start with white light and subtract colours until you achieve the desired colour.

14. Technological Applications • Properties of Light • Fibre optics cables, infrared cameras, laser pointers • Additive Colour Theory • Stage lighting, images on television screens, computer projectors and monitors • Subtractive Colour Theory • The mixing of paints or inks in artistic work, and the use of colour printers

15. Progression through the curriculum • Grade 4 • Understanding Matter and Energy “Light and Sound” • Grade 10 • Academic level - Physics “Light and Geometric Optics • Applied level – Physics “Light and Applications of Optics” • Grade 12 University level • The Wave Nature of Light

16. Special Consideration • Grade 5 • Understanding Earth and Space Systems “Conservation of Energy and Resources” • Grade 6 • Understanding Earth and Space Systems “Space” • Grade 9 • Earth and Space Science: SNC1D “The Study of the Universe”, SNC1P “Space Exploration”

17. Curricular Expectations • Note: Additive and subtractive colour theories are only located in the applied level expectations

18. Gr. 10 Academic Science Relating Science to Technology • E1.1 – analyse a technological device or procedure related to human perception of light and evaluate its effectiveness • E1.2 – analyse a technological device that uses the properties of light and explain how it has enhanced society Understanding Basic Concepts • E3.2 – identify and label the visible and invisible regions of the electromagnetic spectrum • E3.8 –describe properties of light, and use them to explain naturally occurring optical phenomena

19. Gr. 10 Applied Science Relating Science to Technology • E1.1 – analyse how additive and/or subtractive colour theory are applied in technologies used in everyday life • E1.2 – describe the role of selected optical technologies in the transmission of information information, and analyse their impact in society Developing Skills of Investigation and Communication • E2.5 – investigate how various objects or media reflect, transmit or absorb light, and record their observations using ray diagrams • E2.6 – predict the effect of shining a coloured light on objects of different colours, and test their predictions through inquiry Understanding Basic Concepts • E3.2 – identify and label the visible and invisible regions of the electromagnetic spectrum, and identify the colours that make up visible white light • E3.5 – use additive colour theory to predict the results of combining primary and secondary light colours • E3.6 – use subtractive colour theory to describe the effect of colour filters on white light • E3.7 – explain how the colour of an object is determined by reflection, absorption, and transmission of colour • E3.8 – explain how the properties of light or colour are applied in the operation of an optical device

20. Where in the curriculum should these concepts be taught? • Outline for Optics Unit in Applied Science Optical Illusions & History of Light Properties of Light Concave Mirrors Additive Colour theory Convex Mirrors Subtractive Colour theory Refraction of Light Converging Lenses Reflection and Formation of Images Mirrors and Characteristics of Images Diverging Lenses

21. Teaching Strategies • Chalk and talk • Provides reference notes and aids auditory learners • Labs and Investigations • Provides opportunities for self discovery, needs of kinesthetic and interpersonal learners met • Use of spectroscopes, ray boxes, prisms • Literacy Activities • Visual learners are addressed, students can practice note taking/literacy skills

22. Teaching Strategies • Video clips • Bill Nye: Light provides a base level of knowledge and a good introduction • Addresses visual and auditory learners • Visual Aids • Continually provide diagrams which illustrate the concepts being provided • Especially important for subtractive colour theory! • Engages visual learners • Demonstrations & Technology Showcase • Use technology and have students explain how it works with reference to concepts learned in class • Engage learners by showing them “eye brow raisers”

23. Teaching Additive Theory • Teacher-directed Inquiry (TI): • Mix colours of light using filtered flashlights • Predict results and then test predictions • Note: Additive Theory (KU) • Provide the theory behind additive theory through direct instruction and note-taking. • Assignment: How to make a rainbow (CO) • Students read a short paragraph and answer questions on the visible spectrum/additive theory using their notes and the article content. • Quiz (KU) • Evaluate knowledge and understanding • Build an Optical Device Project (A) • Build an optical device of your choice based on theory (stage lighting)

24. Misconception # 1 White light is made up of all the colours of light Strategies for alleviating misconceptions: • Demonstrations • Use of prisms to break apart white light & colour wheel • Literary Activities • How a rainbow is made – read and answer questions on what a rainbow is. • Visual Aids • What is your eye seeing? Refer to the three primary coloured bells • Investigations • Splitting Light investigation – use a prism, spectroscope to examine white light (and light from different types of bulbs)

25. Misconception # 2 A yellow shirt is always a yellow shirt Strategies for alleviating misconceptions: • Demonstrations • Turn off the lights – what colour is the shirt now? • Use filters to filter out one of the colours of light being reflected (green + red = yellow) • Visual aids • Additive colour wheel – remind student that yellow light is a combination of green and red light • What is your eye seeing? Refer to the three primary coloured bells

26. Investigations to Aid Understanding • Splitting Light Lab • Use prisms and spectroscopes to view sunlight (white light) and fluorescent light. Draw the resulting colours that it contains. • Mixing Colours Lab (Additive theory) • Involves a process of predicting the result when mixing various colours of light. Once predictions are made, students use coloured flashlights to test predictions • Subtracting colours lab (Subtractive theory) • Use food colouring, pencil crayons, etc., to mix colours and observe the resulting colours

27. Demonstrations • Let’s See Invisible Light • Filtered flashlights (red, green, blue) • Using light to transmit information • Colour wheel • Diffraction discs

28. Modifications to Aid Students • Provide additive and subtractive colour wheel on assessments – eliminate memorization • For subtractive theory, provide a chart that outlines for each colour; the colours it absorbs and the colours it reflects • Computer simulations to visualize interactions between materials and light

29. Safety Considerations • Inform students not to stare into the sun • Could potentially damage retinas • Provide expectations for the safe use of laser pointers

30. Any Questions? ?