LightPowerPointPresentation-bjsMST.ppt

Light and Sound In this unit: Properties of light Reflection Colours Refraction Properties of sound Hearing Part 1 – Properties of Light Light travels in straight lines: Light travels VERY FAST – around 300,000 kilometres per second. Light travels much faster than sound. For example: We see things because they reflect light into our eyes: Luminous and non-luminous objects Shadows Properties of Light summary Light travels in straight lines Light travels much faster than sound We see things because they reflect light into our eyes Shadows are formed when light is blocked by an object Part 2 - Reflection Reflection from a mirror: The Law of Reflection Clear vs. Diffuse Reflection Smooth, shiny surfaces have a clear reflection: Using mirrors Two examples: Colour White light is not a single colour; it is made up of a mixture of the seven colours of the rainbow. The colours of the rainbow: Red Orange Yellow Green Blue Indigo Violet Adding colours White light can be split up to make separate colours. These colours can be added together again. The primary colours of light are red, blue and green: Seeing colour The colour an object appears depends on the colours of light it reflects. Using coloured light If we look at a coloured object in coloured light we see something different. For example, consider a football kit: In different colours of light this kit would look different: Some further examples: Using filters Filters can be used to “block” out different colours of light: Investigating filters Refraction Sound – The basics Drawing sounds… Drawing sounds… Hearing problems Other sound effects… The Ear The Ear * Laser At this speed it can go around the world 8 times in one second. 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. Homework A luminous object is one that produces light. A non-luminous object is one that reflects light. Luminous object