Presentation on theme: "Light and Sound In this unit: Properties of light Reflection Colors"— Presentation transcript:
1 Light and Sound In this unit: Properties of light Reflection Colors RefractionProperties of soundHearing
2 Part 1 – Properties of Light Light travels in straight lines:Laser
3 Thing that can happen to light DiffractionDiffraction
4 Light travels VERY FAST – around 300,000 kilometers per second. At this speed it can go around the world 8 times in one second.
5 Light travels much faster than sound. For example: 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.
6 We see things because they reflect light into our eyes: Homework
7 Luminous and non-luminous objects A luminous object is one that produces light.A non-luminous object is one that reflects light.Luminous objectsReflectors
8 Properties of Light summary Light travels in straight linesLight travels much faster than soundWe see things because they reflect light into our eyes
9 Part 2 - Reflection Reflection from a mirror: Mirror Normal Incident rayReflected rayAngle of incidenceAngle of reflectionMirror
10 Angle of incidence = Angle of reflection The Law of ReflectionAngle of incidence = Angle of reflectionIn other words, light gets reflected from a surface at ____ _____ angle it hits it.The same !!!
11 Clear vs. Diffuse Reflection Smooth, shiny surfaces have a clear reflection:Rough, dull surfaces have a diffuse reflection.Diffuse reflection is when light is scattered in different directions
12 Using mirrorsTwo examples:2) A car headlight1) A periscope
13 ColorWhite light is not 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” by raindrops.
14 The colors of the rainbow: RedOrangeYellowGreenBlueIndigoViolet
15 Adding colorsWhite 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 makes magenta (purple)Adding blue and green makes cyan (light blue)Adding red and green makes yellowAdding all three makes white again
16 Only red light is reflected Seeing colorThe color an object appears depends on the colors of light it reflects.For example, a red book only reflects red light:HomeworkWhitelightOnly red light is reflected
17 A white hat would reflect all seven colors: A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):Purple lightA white hat would reflect all seven colors:Whitelight
18 Using colored lightIf we look at a colored object in colored light we see something different. For example, consider a football kit:Shirt looks redWhitelightShorts look blue
19 In different colors of light this kit would look different: RedlightShirt looks redShorts look blackShirt looks blackBluelightShorts look blue
20 Some further examples: ObjectColor of lightColor object seems to beRed socksRedBlueBlackGreenBlue teddyGreen camelMagenta bookHomework
21 Using filters Red Filter Filters can be used to “block” out different colors of light:Red FilterMagenta Filter
22 Investigating filters Color of filterColors that could be “seen”RedGreenBlueCyanMagentaYellow
24 Words – speed up, water, air, bent, media RefractionRefraction is when waves ____ __ or slow downdue to travelling in a different _________.A medium is something that waves willtravel through. When a pencil is placed in water it looks like this:In this case the light rays are slowed down by the water and are _____, causing the pen to look odd. The two media in this example are ______ and _______.Words – speed up, water, air, bent, media
26 Words – slowly, low, high, quickly Sound – The basicsWe hear things when they vibrate.If something vibrates with a high frequency (vibrates very ______) we say it has a _____ pitch.If something vibrates with a low frequency (vibrates ______) we say it has a ____ pitch.The lowest frequency I could hear was…Words – slowly, low, high, quickly
27 Drawing sounds… This sound wave has a _____ frequency:
28 Drawing sounds… This sound wave has a _____ amplitude (loud): This sound wave has a _____ amplitude (quiet):
29 Hearing problems Our hearing range can be damaged by several things: Too much ear wax!Damage to the auditory nerve from soundsIllness or infectionsOld age
30 Other sound effects… Like light, sound can be… Reflected – sound reflections are called ______.Refracted – this is why you might sound strange if you try talking underwater
31 The Ear Label your diagram with the following: These bones are vibrated by the eardrumThis tube carries the sound towards the eardrumThis part is used to help us keep our balanceThis part “picks up” the vibrationsThis part of the ear contains many small hairs with turn vibrations into an electrical signalThis part connects the ear to the mouthThis part “channels” the sound towards the ear drum
33 Light Notes- (Write question and answers- keep until test!) 1. What are the colors of the light spectrum?2. What are the primary colors of light?3. If an object is red under a white light, what is being absorbed? What is being reflected?4. If a white light shines through a red filter, what is absorbed? What color shines through?5. If a blue light shines through a red filter, what is absorbed? What color shines through?6. What does a polarizing filter do?7. What causes light to be produced?