1. Light - Overview of light - Properties of light
- Luminous and non-luminous objects
- The strangeness of light
- The electromagnetic spectrum
- Wavelength of frequency
- color & color Blindness
- The production of light
- The speed of light

2. Where does light come from?
The SUN!!
The sun is a star located 1.50 x 108 km, or 1 Astronomical Unit, away from Earth.
It provides energy in the form of light through a process called nuclear fusion.
Nuclear fusion occurs when two atoms that naturally repelled each other are pulled together by a superior force and the atoms fuse together.
Nuclear fusion produces energy that reaches us as heat and light.

3. The sun provides the energy that enables life on Earth.

4. What The Heck Is Light

5. Light travels in straight lines:
Properties of Light
Light travels in straight lines:
Laser

6. Light travels VERY FAST – 3.0X108m/s = 300,000 kilometres per second.
At this speed it can go around the world 7.5 times in one second.

7. Light travels much faster than sound.
For example:
Thunder and lightning start at the same time, but we will see the lightning first.

8. We see things because they reflect light into our eyes:
Homework

9. Luminous and non-luminous objects
A luminous object is one that produces light.
A non-luminous object is one that reflects light.

10. Properties of Light summary
Light travels in straight lines
Light travels much faster than sound
We see things because they reflect light into our eyes

11. The Strangeness of Light
Nothing moves faster than the speed of light
3.0 x 108 m/s
Anything with mass cannot travel at the speed of light
Light is defined as a collection of one or more photons (particles) propagating through space as electromagnetic waves
therefore, it’s a particle and a wave
Unlike heat and sound energy which requires a medium (a physical substance) to move, light does not
Light is transferred through radiation (via electromagnetic waves) in a vacuum

12. Fun Science Light Video

13. Modern electromagnetic waves
Today we have identified many types of electromagnetic waves which makes up our electromagnetic spectrum
The Electromagnetic Spectrum video

14. The Electromagnetic Spectrum
Your eyes can only see the visible part of the EM spectrum, but your hands can feel the infrared part.

15. The Electromagnetic Spectrum
Machines can detect other parts of the EM spectrum, but the information needs to be converted into colours for us to see it.

16. Example – The Sun
visible
x-ray
UVA
UVB

18. As we decrease wavelength, we increase frequency and energy
Modern View Continued
Longer Wavelength
(Low Energy)
Shorter Wavelength
(High Energy)
As we decrease wavelength, we increase frequency and energy

19. Wavelength and Frequency
Wavelength – the distance between successive crests on a wave.
Frequency – the number of cycles a wave goes through in one second.

20. The Visible Light Spectrum
Different colours have different wavelengths!

21. color
White light is not a single color; it is made up of a mixture of the seven colours of the rainbow.
We can demonstrate this by splitting white light with a prism:
This is how rainbows are formed: sunlight is “split up” by raindrops.

22. The colours of the rainbow:
Red
Orange
Yellow
Green
Blue
Indigo
Violet
ROY-G-BIV

23. Adding colours
White light can be split up to make separate colours. These colours can be added together again.
The primary colours of light are red, blue and green:
Adding blue and red makes magenta (purple)
Adding blue and green makes cyan (light blue)
Adding red and green makes yellow
Adding all three makes white again

24. Only red light is reflected
Seeing color
The color an object appears depends on the colours of light it reflects.
For example, a red book only reflects red light :
Homework
White
light
Only red light is reflected

25. A white hat would reflect all seven colours:
A pair of purple pants would reflect purple light (and red and blue, as purple is made up of red and blue):
Purple light
A white hat would reflect all seven colours:
White
light

26. color Blindness
The tricky thing about color blindness is that many people don’t know they are color blind until they get tested
40% of color blind pupils currently leaving secondary school are unaware that they are color blind
There are of course advantages

27. How many animals are there?

28. 6!

29. Red Green color Blindness is caused by a gene on the X chromosome therefore, since males have 1 X and 1 Y while females carry 2 X’s, this issue is predominately found in males (7-10% of the overall population) and is very rarely seen in females.  
For these people, they cannot see red and green light.

30. Blue color Blindness is equally unlikely for both males and females as the deficient gene is found on chromosome 7. These people can’t see blue color light
In both these cases the problem isn't as straight forward as not seeing blue, red or green light.  If what they are looking at contains these colours, they will not be seen.

32. What Colorblind People See

33. What is color Blindness

34. The Production of Light
Light is produced by three main ways:
Incandescence
Hot things glow

35. The Production of Light
Luminescence
Electrons jump around

36. The Production of Light
Chemoluminescence
Chemical reactions
Bioluminescence is a chemical reaction inside a living organism

37. The speed of light
The speed of light in a vacuum is a universal constant.
300,000,000 m/s
The speed of light in a medium is always slower than the speed of light in a vacuum.

38. How long will it take?
Earth
Moon
384,000,000 m
How long does light take to reach the Earth from the Sun?
8.3 minutes

39. Looking Into The Past
By looking at objects in the universe (stars and galaxies), you are looking into the past. Why?

40. Looking Into The Past Time for the light to reach us Object The Moon
1.3 seconds
The Sun
8.3 minutes
Jupiter
35 to 52 minutes
Pluto
5.5 hours
Alpha Centauri (nearest star)
4.3 years
Sirius (Brightest star in our sky)
9 years
Betelgeuse (Another bright star)
430 years
Orion Nebula
1500 years
Andromeda Galaxy
2.5 million years