1. MIRAGES Mirages are actually optical illusions They are usually seen on a very hot day and are a result of how light travels through air at different temperatures The air directly above a hot surface is much hotter than air above it Light travels differently through materials of different densities (refraction) Light is bent as it travels through the hotter air to your eye pavement Bent light path from sky Eye assumes it’s coming from the pavement

2. So now the image comes from the pavement instead of the sky What is supposed to be just blue sky now looks like blue water on top of the pavement

3. THE NATURE OF LIGHT A straight line stream of particles as suggested by Isaac Newton, or … the movement of energy in wave form? We know that particles have mass Does light have mass?

4. NOT REALLY!! So then it must be energy and travel in wave form NOT REALLY!! IT BEHAVES LIKE BOTH!!!

5. Light travels in straight lines suggestive of a beam of particles because it can be blocked by objects …. But it can also go through a substance, suggesting that it travels as a form of energy

6. Albert Einstein suggested that due to the dual particle/wave nature of light, that energy and mass are interchangeable and can be converted one to another E = mc 2 E is energy, m is mass and c is the speed of light There are still lots of missing pieces in our understanding of the nature of light

7. WAVE NATURE OF LIGHT

9. VISIBLE LIGHT Different wavelengths of light can be separated if white light is passed through a transparent prism

10. A blue object absorbs all light wavelengths except blue which is reflected back at you A red object absorbs all light wavelengths except red which is reflected back at you The molecule inside chloroplasts which traps the sun’s energy for use in photosynthesis is called chlorophyll Chlorophyll absorbs all light wavelengths except green which is reflected back Black is the colour of nothing White is the colour of everything

11. RAINBOWS Rainbows are caused by light refracted and separated through millions of tiny water droplets in the air The water droplets are acting like prisms The different colours in a rainbow blend one to the next They are not distinct and separate bands of colour

12. HOW WE SEE COLOUR Our retina is a very thin layer of light sensitive cells The cells are of two different types Rods and Cones Rods detect the presence/absence of light Cones detect colour and don’t work very well in the dark There are three different kinds of cones: one detects red light, one detects green light and one detects blue light

13. Colours besides red, blue and green are produced by different amounts of these colours combined together This is slightly different than mixing paint colours together Colour blindness is caused by an inadequate or weaker supply of a certain type of cone and is more prevalent in males than females

14. BEYOND LIGHT

15. RADIO WAVES Longest wavelength, lowest frequency

16. INFRARED RADIATION heat radiation Anything that is warmer than its surroundings will emit infrared rays Warmer areas are yellow, orange and red; colder areas are green, blue and black

17. VISIBLE LIGHT

18. ULTRAVIOLET RADIATION Never look directly at the sun U V light is damaging Ow! The ozone layer in the earth’s atmosphere blocks out much of the damaging U V radiation, however in recent years, the ozone layer has been thinning because of chemicals that we put in the air.

19. That leather look (and feel) is not a jacket

20. MELANOMA – TERMINAL SKIN CANCER

21. X RAYS Broken dog leg Dental x-rays showing fillings Can easily pass through soft tissue like skin and muscle

22. GAMMA RAYS Highest frequency, shortest wavelength Very energetic and very penetrating Exposure to high doses of gamma rays causes cancer Causes radiation sickness

23. EXTENDING NIGHT VISION Works two ways Magnifying the small amount of light that is actually there or … Capture and visualize the infrared radiation that is emitted

24. LASER LIGHT Transmitting data between satellites with laser light Concentrated light of a single wavelength Very precise; so precise, it can cut glass and metal