1. Interactions of Light Waves and Matter

2. Interactions of Light Waves and Matter
When light strikes any form of matter, it can interact with the matter in three ways:
It can be reflected.
It can be absorbed.
It can be transmitted.
Or most likely, some combination of these happens.

3. Absorption of Light
Absorption (in optics): the transfer of light energy to particles of matter
What happens to the matter that absorbs the light energy?
Answer
It gains heat energy.
How do you know?
Which cat will feel warmer in the sun?

4. Scattering of Light
Scattering is an interaction of light with matter that causes light to change its energy, direction of motion, or both.
Light is scattered when it is absorbed by matter and then emitted in different directions.
Find out how scattering makes the sky blue. Read:

5. Transmission of Light
Transmission is the passing of light or other forms of energy through matter.
Light is easily transmitted through transparent substances.
Translucent substances transmit some of the light and absorb or scatter some of the light.
Opaque substances absorb and/or reflect all the light.

6. Refraction Bill Nye the Science Guy on Refraction

7. Refraction
Refraction is the bending of a wave when it enters a medium where its speed is different.
The wave must be entering the new medium at an angle for this to happen.

8. Refraction and Optical Illusions

9. Refraction and Optical Illusions
Magnifying Glass
Invisible iBalls
Making a Penny Disappear
Disappearing Bottle
Do the disappearing penny activity

10. Colors of Light Ludwig Von Drake
Bill Nye: Light and Color

11. Visible Light
Visible light is the very narrow range of wavelengths and frequencies in the electromagnetic spectrum that humans can see.
Visible light waves have wavelengths between 400 nm and 700 nm ROY G BiV

12. Prisms A prism is an example of refraction in action.
When light is refracted, the amount that the light bends depends on its wavelength.
Waves with short wavelengths bend more than waves with longer wavelengths.
Experiment with prisms

13. Adding Colors of Light
SciZone - Ontario Science Centre: Mixing Colours
Primary Light Colors: Blue, Green, and Red
Secondary Light Colors: Cyan, Magenta, and Yellow
Use three color lights to demonstrate

14. The Color of Opaque Objects
The color of an object is determined by what color or colors it reflects.
What colors are reflected by the following objects?

15. Pigments
A pigment is a substance that gives another substance or mixture its color.
Two examples:
Chlorophyll – makes leaves green
Melanin – give skin its color

16. Pigments
Primary pigment colors: Yellow, Cyan, and Magenta – these combine to make black
Secondary Pigments: Green, Blue, and Red

17. Color Subtraction Each pigment absorbs at least one color of light.
When you mix pigments together, more colors are absorbed or taken away so mixing pigments is called color subtraction.
Recall the experiment where we separated black ink into red and blue and green ink into yellow and blue.

18. Diffraction
Diffraction is the bending of waves around barriers or though openings.
The amount a wave diffracts depends on its wavelength and the size of the barrier or opening.
Demonstrate with diffraction grating

19. Diffraction

20. Interference
Interference is the combination of two or more waves that results in a single wave
In constructive interference the resulting wave has a greater amplitude than the original waves had.
In destructive interference the resulting wave has a smaller amplitude than the original waves had.
Interference can cause bright and dark bands to form.