1. Light and Sound Waves In these notes: Properties of light
Reflection & Refraction
Properties of sound

2. Parts of a Wave

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

4. Light travels VERY FAST – around 300,000 kilometres 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 objects
Reflectors

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

9. 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

10. Part 2 - Reflection Reflection from a mirror: Mirror Normal
Incident ray
Reflected ray
Angle of incidence
Angle of reflection
Mirror

11. 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 !!!

12. 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

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

14. Words – speed up, water, air, bent
Refraction
Refraction is when waves ____ __ or slow down due to travelling in a different _________. 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

17. Color
White light is not a single color; it is made up of a mixture of the seven colours 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.

18. Words – slowly, low, high, quickly
Part 3: Sound
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.
The lowest frequency I could hear was…
Words – slowly, low, high, quickly

19. Drawing sounds… This sound wave has a _____ frequency:

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

21. 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