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What is light
- 1. What Is Light? In this Powerpoint presentation: 1) Properties of light 2) Colors ) 3) Reflection - Mirrors f 4) Refraction - Lenses
- 2. Properties of Light Lighttravels in straight lines: LASER
- 3. Light travels muchfaster than sound. For example: 1) Thunder and lightning start at the same time, but we will see the lightning first. 2) When a starting pistol is fired we see the smoke first and then hear the bang.
- 4. Light travels VERYFAST – about 300,000 kilometers per second or 186,000 186 000 miles per second second. At this speed light could travel the equivalent of 8 times q f around the world in one second!
- 5. Light can createshadows Shadows are places where light is “blocked”: Rays of light
- 6. Light travels inwaves A wave is a disturbance that transfers energy from place to place. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 7. What characteristics dolight waves h have? ? Light waves are like other kinds of waves. They have crests, troughs, wavelength, frequency and speed. However, light waves are electromagnetic! Light waves have a component that is electric and magnetic!! QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 8. We see thingsbecause they g y reflect light into our eyes! This is literally the only way we get to see things! ALL objects we see either create light or reflect light!! Homework H k
- 9. Light is aform of energy called Electromagnetic Radiation - Electromagnetic Radiation comes f El i R di i from the sun and h d other sources QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 10. Electromagnetic Radiation •Travels atthe speed of light •Is mostly i i ibl I tl invisible •Carries energy •Is VERY important to Is QuickTime™ and a TIFF (Uncompressed) decompressor society and is something are needed to see this picture. YOU can’t be without for many reasons
- 11. Types of electromagnetic radiation Radio and TV - Great for broadcasting Microwave-Super for cell phones, microwaves Infrared-Think HEAT Visible Light - Yep, it’s how we see Ultraviolet Invisible, can cause c ncer; Ultr vi let - Invisible c n c use cancer; kills germs erms Xray- images of bones and teeth; space exploration Gamma - treating cancer (radiation therapy)
- 12. Properties of Lightsummary 1) Light travels in straight lines and is a form of energy 2) Light travels much faster (a million times faster!) than sound 3) We see things because they reflect light into our eyes e es 4) Shadows are formed when light is blocked by an object 5) Visible light is only a small part of the electromagnetic spectrum; the other parts are invisible to the human eye but not necessarily the um y u y eyes of other animals.
- 13. Part 2 -Reflection and Mirrors
- 14. Regular vs. DiffuseReflection Smooth, shiny surfaces m , y u f have a regular reflection: Rough, dull surfaces have h d ll f h a diffuse reflection. Diffuse reflection is when light is scatt r in ght s scattered n different directions
- 15. Using mirrors Two examples: 2) A car headlight 1) A periscope
- 16. Types of Mirrors:Plane, Concave, Convex QuickTime™ and a TIFF (Uncompressed) decompressor QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Plane mirrors are flat and make “virtual images”. Th images is “virtual” because the im s” The im s i t l” b s th light rays do not come from the image, they only appear to
- 17. Concave Mirrors arecurved inward - just remember, you go “i ” t a cave, and “in” to a b “in” to d “i ” t concave mirror! Virtual Real QuickTime™ and a images TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a image TIFF (Uncompressed) decompressor QuickTime™ and a are needed to see this picture. TIFF (Uncompressed) decompressor are needed to see this picture. The “mirage” box on Mr. S’s desk is g made of two concave mirrors. Images of concave mirrors can be virtual or real! i t l l! QuickTime™ and a QuickTime™ and a TIFF (Uncompressed) decompressor TIFF ( (Uncompressed) decompressor ) are needed to see this picture. are needed t see thi picture. d d to this i t
- 18. Convex mirrors aremirrors that curve outward QuickTime™ and a TIFF (Uncompressed) decompressor QuickTime™ and a QuickTime™ and a are needed to see this picture picture. TIFF (Uncompressed) decompressor ( p ) p are needed to see this picture. d d hi i TIFF (Uncompressed) decompressor are needed to see this picture. Convex mirrors are used for security purposes, in cars etc. They ll Th allow us to see a wide st s id QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. view. The images they make are virtual QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture picture.
- 19. Review of Reflection 1.Two types of reflection, regular and diffuse 2. Mirrors come in 3 types: plane, convex and concave. Each has a distinct shape and use. 3. Mirrors can make virtual images or real images depending on their type 4. Virtual images - light rays do not meet and the image is always upright or right-side-up m g y p g g p 5. Real images - always upside down and are formed when light rays actually meet
- 20. Refraction •Refraction is whenwaves speed up or slow down due to travelling in a different medium g •A medium is something that light waves will travel through •Light rays are slowed down by the water •Causes the ruler to look bent at the surface • The mediums in this example are water and air
- 21. The degree thatlight bends when it enters a g g new medium is called the “index of refraction”
- 22. Light hitting Light hittingat an straight on is angle is bent not bent
- 23. Lenses work becauseof refraction! Light is bent as it enters a new medium glass! medium, Convex lenses QuickTime™ and a QuickTime™ and a TIFF (Uncompressed) decompressor QuickTime™ and a picture. are needed to see this picture TIFF (Uncompressed) decompressor ( p ) p TIFF (Uncompressed) decompressor ( p ) p are needed to see this picture. are needed to see this picture. 1. 1 Thicker middle, Thick r in middl thin on edges n d s 2. Light rays meet to form a focal point 3. 3 Makes real images since light rays come together from a light source, but can also make virtual images (center picture) 4. Used i 4 U d in cameras, t l telescopes, human eye h QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 24. Concave Lenses QuickTime™ and a QuickTime™ and a TIFF (Uncompressed) decompressor TIFF (Uncompressed) decompressor are needed to see this picture. are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture picture. 1. Concave lenses are thin in the middle and thicker on the edges 2. Since light rays never meet with this lens, they make virtual images only 3. Used in cameras & telescopes to correct spherical aberation, and also eyeglasses
- 25. Review of Refraction 1.Light rays slow down when they enter a new medium di 2. Refraction can cause light rays to change their direction 3. All transparent materials have their own p “index of refraction” 4. 4 Light is refracted when it passes through lenses and this creates images
- 26. Color Part 3 -Color In this section of the Powerpoint you will learn about color and how we can mix colors to create other colors. We will also learn how light helps us to see various colors around us us.
- 27. Yes, we LOVEcolor! QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 28. Color White light isnot a single color; it is made up of a mixture of the seven colors of the rainbow. We can demonstrate this by splitting white light with a prism: This is how rainbows are formed: sunlight is “split up” g p p by raindrops.
- 29. The colors ofthe rainbow: Red Orange Yellow Green Blue Indigo Just remember ROY G. BIV Violet
- 30. Adding colors oflight White light can be split up to make separate colors. These colors can be added together again. The primary colors of light are red, blue and green: Adding blue and red Adding blue and m makes magenta m g green makes cyan g m y (purple) (light blue) Adding red Adding all and green g three makes makes yellow white again
- 31. Seeing color The coloran object appears depends on the colors of light it reflects. For example, a red book only reflects red light: p y g White Only red light light is reflected fl d
- 32. In different colorsof light this shirt would look different: Red Shirt looks red light Shorts look black Shirt looks black Blue light Shorts look blue
- 33. A pair ofpurple trousers would reflect purple light (and red and blue, as purple is made up of red and blue): Purple light A white hat would reflect all seven colors: White light
- 34. Using filters Filters canbe used to “block” out different colours of light: Red R d Filter Magenta Filter Fl
- 35. Some further examples: Color object Object Color of light seems to be Red Red Red socks Blue Black Green Black Red Black Blue teddy Blue Green Red Green camel Blue Green Red Magenta book Blue Green
- 36. Investigating filters Color offilter Colors that could be “seen” seen Red Green Blue Cyan Magenta Yellow
- 37. Red Blue Green White Yellow Cyan Magenta
- 38. Part 2 -Reflection and Mirrors Mi Reflection from a mirror: Normal Incident ray y Reflected ray y Angle of Angle of incidence reflection Mirror
- 39. The Law ofReflection Angle of incidence = Angle of reflection In other words, light gets reflected from a surface at g g ____ _____ angle it hits it. The Th same !!!
- 40. Brain Pop Movieon Color p Brain Pop Movie on Color! Enjoy it! p j y View the movie on Color from Brain Pop. Then take the p quiz at the end of the movie. How did you do?