1. WHAT IS LIGHT?
INTRODUCTION

2. CAMERA ON A PILL
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What is this got to do with optics?

3. What does optics mean?
Physical
properties of
light

4. Light and Colour
Why does bright lights seem to make things more vivid at night?

5. U2 360 Tour

6. How can white light allow us to see objects with so much colour
How can white light allow us to see objects with so much colour? Why is the sky blue?

7. Reasons: White light contains all of the colours of the rainbow.
The sky is blue because the particles like water vapour in the air reflect the colour blue and absorb all the other colours found in white light

8. Sources of Light

9. 1) Natural Sources of Light

10. SUN!
most important natural source of light

11. Other Stars

12. Lightning

13. Fires

14. Bioluminescence ability of organisms to produce light
90 % of all sea creatures can
in very deep water no light reaches
use light to see prey
scare predators
camouflage
some produce their own
some contain bacteria that produce light

15. angler fish
long spine with a bulb
used as a lure to attract prey

16. Jellyfish
use light to attract fish into their tentacles

17. Flashlight fish
use light to help to keep in a school

18. Fireflies
attract mates by chemical reactions

19. 2) Artificial Light

20. Incandescent Light produced by metals at very high temperatures
bulbs contain a filament or thin wire (tungsten)
uses electricity to heat up
filament emits light as a way to release some energy as a glow

21. Fluorescent Light bulb such as gas such as mercury vapour
mercury vapour is exposed to electricity which emits UV light
bulb is coated with a white powder called phosphor
phosphor glows after exposed to UV radiation

22. Compact Fluorescent Bulbs
even though compact fluorescent lights are more efficient than incandescent light bulbs, still 80% of energy is converted into heat

23. Phosphorescent Light ability to store energy from radiation
different from fluorescent since phosphor needs UV light
phosphorescent materials glow in the dark for some time after being energized by light
glow in the dark will fade but can re-energize with a light source

24. Chemiluminescence
light produced from chemical reactions (no heat or temperature change)
“cool light”
bioluminescence are also forms
ex. luminol used in forensics: glows when it reacts to iron in blood
ex. glow sticks

25. How Glow Sticks Work

26. Triboluminescence light producing from friction
rubbing crystals together
quartz used in rattles in Aboriginal people flashes light
breaking crystals or rubbing diamonds

27. Electric Discharge
produce light using electric current through air or another gas
halogen gases used often
ex. carbon-arc involves passing a current through the air between 2 rods