1. the study of the behaviour of light
Optics
the study of the behaviour of light
½ page Mind map…

4. This generates shadows.
Light is often described in terms of rays that travel in straight lines.
This generates shadows.
A Bust of Mr Shilloete.

5. Many rays fan out from a light source but each ray travels in a straight line.

7. Surveyors use the “straight line” nature of light with lasers.

9. Light travels through a vacuum.

10. Light travels at ms-1.
This speed is a significant “constant” and is given its own special symbol - c.

11. Journey to the moon
This diagram shows how long light, rocket, supersonic jet or a runner to reach the moon.

12. glass
silver
Mirrors are backed by a very thin layer of metal which reflects the light.
paint

13. Mirrors produce an upright, virtual image that is laterally inverted
Lateral Inversion
Virtual
Cannot be projected onto a screen.

14. mirror clock mirror clock The clockface faces the mirror.
NCEA
mirror
The clockface faces the mirror.
Sketch the image of the clockface in the mirror.
clock
mirror 12 6
clock

15. mirror clock mirror clock The clockface faces the mirror.
NCEA
mirror
The clockface faces the mirror.
Sketch the image of the clockface in the mirror.
clock
mirror 12 6
clock

16. i = r Law of reflection i = incident angle r = reflected angle
measured from the normal
r = reflected angle
A line  to the surface at the point of incidence
i = r
Law of reflection

17. Angle of incidence
Angle of reflection =
i = r

18. Image in a Plane Mirror
Mirror
Object
Image
Plane mirror activity

19. NCEA
Copy the diagram accurately and draw in the paths of the reflected light rays, hence show the position of the image and the lines to show how the image was formed. //
normal
ACCURACY TO ± 1O

20. ACCURACY TO ± 1OIncident and final reflected ray must be parallel.
Two plane (flat) mirrors are fixed exactly at right angles (90º) to each other, as shown in the diagram below. A ray of light is aimed at one of the mirrors as shown.
Copy this diagram and accurately draw rays to show how this ray reflects.
NCEA
ACCURACY TO ± 1OIncident and final reflected ray must be parallel.

21. Two plane (flat) mirrors are fixed exactly at right angles (90º) to each other, as shown in the diagram below. A ray of light is shown.
Explain what would happen to the light rays if the mirrors were placed at an angle greater than 90° to each other.
Using diagrams may help you with your answer.
NCEA
<135o
> 135o
As the angle between the mirrors increases (greater than 900) the incident ray and the final ray diverge more and more until the 1st reflected ray misses the second mirror altogether.

23. Ex: glossy vs. flat paint

24. The smooth plane mirror is in a room with a rough concrete floor.
The light intensity is even over the whole room.
Which of the two surfaces will receive the most light?
Which of the two surfaces will reflect an image?
Explain your answers.
The plane mirror
The concrete surface

25. The plane mirror The concrete surface
The smooth plane mirror is in a room with a rough concrete floor.
The light intensity is even over the whole room.
Which of the two surfaces will receive the most light?
Which of the two surfaces will reflect an image?
a) Both surfaces will receive the same amount of light
The plane mirror
The reflected light is not scattered in the mirror so a virtual image is formed.
The reflected light is scattered by the concrete so an image is not formed
The concrete surface

26. Multiple Reflections ( 2 or more mirrors)
object
image
image
image