Light and Optical Systems PDF

Light and Optical Systems Topic 1 What is Light? What is Light? Light is a form of energy that you can see. This energy can be produced naturally or artificially, by light producing technologies. Natural Light Sources These are not man-made in any way. Examples include - Sun, stars, lightn...

Light and Optical Systems Topic 1 What is Light? What is Light? Light is a form of energy that you can see. This energy can be produced naturally or artificially, by light producing technologies. Natural Light Sources These are not man-made in any way. Examples include - Sun, stars, lightning, etc. Artificial Light Sources First Basic Principle of Light The first basic principle of light is that light is a form of energy. When light reaches a surface, it can be absorbed and transformed into other types of energy. First Basic Principle of Light Types of Energy Transformations Electrical: solar panels or batteries change light into electricity Thermal: camera change light into thermal images, black sweaters gain thermal energy (thermal = heat) Chemical: trees convert light energy into sugar First Basic Principle of Light The brightness, or intensity of light indicates how much energy a surface will receive. Brainstorm: How do animals and plants respond to changes in light intensity??? Sources of Light Today, we are lucky to have many different sources of light available to us. In fact light pollution can be a problem in major cities as it can wash out our view of the night skies. To decrease light pollution, streetlights are now designed to direct light downward and we are using lights that are more energy efficient. Protect the night: Sea Turtles https://www.youtube.com/watch?v=Rq-MVXdXc3Q https://youtu.be/GFOuJuSENPc https://www.sciencealert.com/watch-the-dra matic-effect-light-pollution-has-on-our-view-o f-the-night-sky Ikea Lamp - natural or Artificial light? https://www.youtube.com/watch?v=dBqhIVyfsRg Incandescent Light Sources An object can be heated to such a high temperature that it emits visible light. Show the energy transfer Electrical energy Thermal Energy Visible light energy 95% of the energy from incandescents is released as heat! Fluorescent Light Sources In this process, high energy invisible ultraviolet radiation is absorbed by particles, and then the particles glow. This glow is called fluorescence. UV light energy energy absorbed by particles visible light energy Fluorescent Light Sources Disadvantages to this type of light is that they are expensive to produce and hard to dispose of as they are made of toxic materials. However, because they emit no thermal energy, they are not hot to the touch and are more energy efficient. What do we do when they are burned out????? Phosphorescent Light Sources Their energy transfer is similar to fluorescent bulbs. the difference is that phosphorescent particles store this energy and release it more slowly. They continue to glow after the source of light has been removed Summary of Energy Transfer UV light energy energy absorbed by particles visible light energy (stored, them emitted over a longer period of time) Chemiluminescent Light Sources Light can result from the energy emitted from chemical reactions. Chemical energy visible light energy Example: Deep thoughts: Where does the glow go when you throw it away? Bioluminescent Light Source This is a special kind of light produced by living creatures. The purpose of this could be to allow the animal to see in places like the deep ocean where light cannot penetrate, to attract mates and prey. Anglerfish Mating https://www.youtube.com/watch?v=XhsyZnVx2rQ All objects that emit light are called luminous. The brilliance of bioluminescence https://www.youtube.com/watch?v=oKjFVBV Gad0 Review Light is a form of energy. Energy can only be transformed or transferred. All sources of light transform different kinds of energy (chemical, electrical, etc) into visible light energy. Light Exploration Materials: Ray box, mirror, prisms, screen (use a wall or a piece of paper ) Groups of 3 Spend time exploring what happens to light with these objects. Be inquisitive! Ex: shine light - on a mirror, on the box, through the prisms (both the clear and non clear side) Does it move differently through different prisms? Can you line up TWO mirrors? Does light bend? Can you get a shadow to form? Can you change the size of the shadow? If you mess around, you sit! Ray Model of Light A ray is a straight line that represents the path of a beam of light. Light travels in a straight line. A ray diagram will show you what happens when light rays reach different types of materials Ray Model of Light What inference can you make about the size of the shadow and the distance from the light source? Behavior of Light A transparent object is one that lets light pass through with no shadows formed. We can see everything through this material. Ex: windows Behavior of Light A translucent object lets only some light go through (not all)and forms a shadow that is very light and no image is visible (we can see light through) Behavior of Light An opaque object lets no light pass through and forms a shadow What is Light? Dr Binoc https://www.youtube.com/watch?v=d7yTlp4gBTI  Type of How we see What happens to light rays Ray Diagram Examples material through this when it strikes the material material (choose one) (choose one) Opaque see everything transmitted (go through) see nothing scattered (some go through, see light only but some bounce back not images absorbed (all bounced back) Translucent see everything transmitted (go through) see nothing scattered (some go through, see light but not some bounce back images absorbed (all bounced back) Transparent see everything transmitted (go through) see nothing scattered (some go through, see light but not some bounce back images absorbed (all bounced back)  Type of How we see What happens to light rays Ray Diagram Examples material through this when it strikes the material material (choose one) (choose one) Opaque see everything transmitted (go through) see nothing scattered (some go through, see light only but some bounce back not images absorbed (all bounced back) Translucent see everything transmitted (go through) see nothing scattered (some go through, see light but not some bounce back images absorbed (all bounced back) Transparent see everything transmitted (go through) see nothing scattered (some go through, see light but not some bounce back images absorbed (all bounced back) Remember that in translucent objects, some rays are also bounced back.t Material Classification Behaviour of light glass white clouds stained glass window aluminum foil fog card board wax paper black chalkboard Material Classification Behaviour of light glass transparent transmitted white clouds translucent scattered stained glass window translucent scattered aluminum foil opaque absorbed fog translucent scattered card board opaque absorbed wax paper translucent scattered black chalkboard opaque absorbed