The Ray Model of Light Part 1 Properties

The Ray Model of Light

Part 1 – Properties of 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.

• 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.

• 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

3 Classifications of Matter Recall: • A transparent object lets light pass through it easily

3 Classifications of Matter Recall: • A translucent object allows some light to pass through

3 Classifications of Matter Recall: • An opaque material does not let any light pass through it

• 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 light from any surface

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

Activity • In your lab groups, try Activity 11. 5 on Page 482 and 483

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 !!!

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

Specular Reflection • Specular reflection is the reflection of light off a smooth surface The water acts like a plane mirror Disco rules!

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