1. What is Light?

2. What Is Light?
Energy!

3. Energy….
Usually needs a medium for transmission.
Ex. Heat transfers by
convection or
conduction.

4. Light Energy…..
Travels through the vacuum of outer space…..
Transferred by radiation in the form of an electromagnetic wave

5. Travels in straight lines. Travels VERY fast. - travel at a speed of
Properties of Light
Travels in straight lines.
Travels VERY fast.
- travel at a speed of
3.00 X 108 m/s

6. Electromagnetic Waves
An electromagnetic wave is a wave of energy that moves through space

7. Different electromagnetic waves have different lengths which give them different amounts of energy

8. Electromagnetic Spectrum

9. Electromagnetic Spectrum
Gamma rays
X-rays
Ultraviolet light
Visible light
Infrared light
Microwaves
Radio waves
(pg. 466)

10. But we don’t see radio
waves and x-rays…..

11. Our ears can not hear some high sound frequencies that dogs can.
Radiometer and hot iron
E3.2 identify and label the visible and invisible regions of the electromagnetic spectrum
Similarly our eyes can not “see” some of the wavelengths of light.

12. Visible Light!
Any electromagnetic wave that the human eye can detect.
Called the Visible Spectrum.

13. - white light breaks into the colours of a rainbow when it passes through a prism. - white light is made of all the colours of the visible spectrum
Sir Isaac Newton’s full name with title is easy to remember because of his initials (i.e. SIN)

14. Similarly….
A rainbow appears
in the sky from
the sun’s rays.

15. So….when light from the sun is broken down, its’ spectrum looks like
Encourage students to make up their own mnemonic for remembering the order of rainbow colours.
Let them know “A mnemonic is just a way to remember simple lists”
To show students a very good full spectrum see
Note the Capital letters denote the Additive Primary colours. More on this later in “Seeing Colour.ppt”
Isaac Newton named the colors of the spectrum we use today. At first he only identified 5 colours (red, yellow, green, blue, violet) He changed this to seven colors out of a mistaken belief, derived from the ancient Greeks. They believed there was a connection between the colors, the musical notes, the known objects in the solar system, and the days of the week. Newton therefore added Orange and Indigo to make up 7 names for the main colours of he spectrum i.e. ROYGBIV, Red, Orange, Yellow, Green, Blue, Indigo, Violet
The sun’s light is therefore
White Light.

16. When light from some sources is broken down, it’s Spectrum looks like a series of lines.
Students will benefit by viewing various light sources including Spectrum Tubes through Spectroscopes. This will clearly demonstrate most light is really made up of a series of pure colours

17. The Visible Light Spectrum is a very small part of a much larger spectrum called the Electromagnetic Spectrum
E3.2 identify and label the visible and invisible regions of the electromagnetic spectrum

18. How Do You Remember the Colours?
All the colours spell the name
Roy G Biv
(but that’s boring!)

19. Words to remember the Electromagnetic Spectrum from Long to Short Wavelength
Radio Waves
Microwaves
Infra Red
Visible Spectrum
Ultra Violet
X-Rays
Gamma Rays
Raul's
Mother Is
Visiting
Uncle
Xavier's
Garden
Rabbits
Mate In
Very
Unusual
eXpensive
Gardens
Raging
Martians
Invade
Roy G. Biv.
Using
X-rays
& Gamma Rays
E3.2 identify and label the visible and invisible regions of the electromagnetic spectrum

20. Las Vegas Light Show

21. What is BLACK Light?
A lamp that emits electromagnetic radiation almost exclusively in the soft near ultraviolet range.
Only a very small fraction of visible radiation is emitted, and it is seen as violet/blue light!

22. Playing with Light! Ray box 2 prisms
Draw what you see under the light rays!

23. Vocabulary!
Medium, Convection, Conduction Radiation Electromagnetic Wave Electromagnetic Spectrum Visible Light Prism

24. Homework!
Pg. 469 # 2 - 9

25. Newton noted that the individual coloured lines could not be separated further. These lines are pure colours and are identified by a frequency and wavelength number.