The Ray Model of Light

1. The Ray Model of Light

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

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

4. 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.

5. 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

6. 3 Classifications of Matter • Recall: • A transparent object lets light pass through it easily

7. 3 Classifications of Matter • Recall: • A translucent object allows some light to pass through

8. 3 Classifications of Matter • Recall: • An opaque material does not let any light pass through it

9. 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

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

11. Activity • In your lab groups, try Activity 11.5 on Page 482 and 483

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

13. 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

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

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