the ray model of light. light travels in straight lines: laser part 1 – properties of light
TRANSCRIPT
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The Ray Model of LightThe Ray Model of Light
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Light travels in straight lines:
Laser
Part 1 – Properties of Part 1 – Properties of LightLight
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Light travels VERY FAST – around 300,000 kilometres per second.
At this speed it can go around the world 8 times in one second.
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• A luminous object like a candle radiates light in all directions• We can use a light ray, which is a line and arrow showing the direction light is travelling, to show this.
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• Using Light rays to show the path of light striking an object is called Geometric Optics
• When light emitted from a source (the Sun) strikes an object (Earth), it is called Incident Light
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Recall:
• A transparent object lets light pass through it easily
3 Classifications of 3 Classifications of MatterMatter
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Recall:
• A translucent object allows some light to pass through
3 Classifications of 3 Classifications of MatterMatter
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Recall:
• An opaque material does not let any light pass through it
3 Classifications of 3 Classifications of MatterMatter
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• An image is a reproduction of an original object that is produced through the use of light
• A mirror is any polished surface that exhibits reflection• Reflection is simply the
bouncing back of lightfrom any surface
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Part 2 - ReflectionPart 2 - ReflectionReflection from a mirror:
Incident ray
Normal
Reflected ray
Angle of incidence
Angle of reflection
Mirror
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ActivityActivity
• In your lab groups, try Activity 11.5 on Page 482 and 483
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The Law of ReflectionThe Law of Reflection
Angle of incidence = Angle of Angle of incidence = Angle of reflectionreflection
In other words, light gets reflected from a surface at ____ _____ angle it hits it.
The same !
!!
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Clear vs. Diffuse ReflectionClear 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
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Specular ReflectionSpecular Reflection
• Specular reflection is the reflection of light off a smooth surface
The water acts like a plane mirror Disco rules!
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Using mirrorsUsing mirrorsTwo examples:
1) A periscope
2) A car headlight