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Light travels in straight lines:

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Presentation on theme: "Light travels in straight lines:"— Presentation transcript:

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

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

3 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.

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

5 Luminous and non-luminous objects
A luminous object is one that produces light. A non-luminous object is one that reflects light. Activity 1: Copy and complete ( 4 examples) Luminous objects Reflectors

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

7 Properties of Light summary Activity 2: Copy notes
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

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

9 Angle of incidence = Angle of reflection
The Law of Reflection Angle of incidence = Angle of reflection Activity 3: Fill in missing words In other words, light gets reflected from a surface at ____ _____ angle it hits it. The same !!!

10 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

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

12 Refraction Activity 4: Fill in the missing words
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

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