Light and Sound Properties of light Reflection Colours Refraction http://studyjams.scholastic.com/studyjams/jams/science/energy-light-sound/light.htm Properties of light Reflection Colours Refraction Diffraction Properties of sound Hearing

Part 1 – Properties of Light Light travels in straight lines: Laser

Light travels VERY FAST – around 300,000 kilometres per second. At this speed it can go around the world 8 times in one second.

electromagnetic spectrum

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.

We see things because they reflect light into our eyes: Homework

Shadows Shadows are places where light is “blocked”: Rays of light

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 http://studyjams.scholastic.com/studyjams/jams/science/energy-light-sound/light-absorb-reflect-refract.htm

Part 2 - Reflection When a wave balance off an object at a angle Like a reflection from a mirror: Normal Incident ray Reflected ray Angle of incidence Angle of reflection Mirror

Angle of incidence = Angle of reflection The Law of Reflection Angle of incidence = Angle of reflection In other words, light gets reflected from a surface at ____ _____ angle it hits it. The same !!!

Using mirrors Two examples: 2) A car headlight 1) A periscope

Diffraction of Waves Diffraction involves a change in direction of waves as they pass through an opening or around a barrier in their path. Water waves and sound have the ability to travel around corners, around obstacles and through openings.

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: Adding blue and red makes magenta (purple) Adding blue and green makes cyan (light blue) Adding red and green makes yellow Adding all three makes white again

Only red light is reflected Seeing colour The colour an object appears depends on the colours of light it reflects. For example, a red book only reflects red light: Homework White light Only red light is reflected

A white hat would reflect all seven colours: A pair of purple 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 colours: White light

Using coloured light If we look at a coloured object in coloured light we see something different. For example, consider a football kit: Shirt looks red White light Shorts look blue

In different colours of light this kit would look different: Red light Shirt looks red Shorts look black Shirt looks black Blue light Shorts look blue

Red Blue Green White Yellow Cyan Magenta

Words – speed up, water, air, bent Refraction Reflection involves a change in direction of waves when they bounce off a barrier A medium is something that waves will travel through. When a pen 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 mediums in this example are ______ and _______. Words – speed up, water, air, bent

Words – slowly, low, high, quickly Sound – The basics http://studyjams.scholastic.com/studyjams/jams/science/energy-light-sound/sound.htm We 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. Words – slowly, low, high, quickly

Drawing sounds… This sound wave has a _____ frequency:

Drawing sounds… This sound wave has a _____ amplitude (loud): This sound wave has a _____ amplitude (quiet):

Hearing problems Our hearing range can be damaged by several things: Too much ear wax! Damage to the auditory nerve Illness or infections Old age (not like Mr Richards)