1. Part 2: Behaviors of Light

2. Speed of light In a vacuum, the speed of light is 300,000,000 m/s
Light travels slower as the medium gets denser.
Example: Light will travel slower in water than in air.
When light changes mediums, the speed and wavelength change. Frequency remains the same.

3. Light travels in straight lines
Light will travel in a straight line until it strikes a surface
Laser

4. Luminous and non-luminous objects
A luminous object is one that produces light.
A non-luminous object is one that reflects light.
Luminous objects
Reflectors
-Light Bulbs
-The Sun
-Computer Screens
-The moon
-Your Shirt
- Paper

5. Reflection
The color an object appears depends on the colors of light it reflects.
Reflection occurs any time all or part of a light waves bounces back from a surface.
Homework
White
light
Only red light is reflected
For example, a red book only reflects red light:

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

7. The colors of the rainbow:
Red
Orange
Yellow
Green
Blue
Indigo
Violet

8. The Normal
The normal is an imaginary line from which angles are measured. It is always drawn perpendicular to the surface of the medium.

9. Frequency remains the same
Refraction
The bending of a wave when it passes at an angle from one medium to another medium
Remember: waves travel at different speeds through different substances.
Frequency remains the same

10. If angle of incidence = 0, no refraction takes place

11. Refraction
Wave that goes from higher velocity to lower velocity bends toward normal
Faster medium = greater angle
Slower medium= smaller angle
Measured from normal

12. Refraction
Wave that goes from lower velocity to higher velocity bends away from normal

13. Refraction
For the following diagrams draw (1) the normal, (2) the direction of the wave if it did not bend, and (3) the direction of the wave if it did bend. Өr Өi Өi Өr Өr Өi
Normal Өi Өr
Straight line path

14. Refraction

15. Reflection:
Reflection is when waves bounce off the surface of a medium. Light reflects differently off a smooth surface than off a rough surface as shown below.

16. Reflections Specular reflection Smooth surfaces
Reflected light remains organized

17. Reflections Diffuse reflection Rough surfaces Reflected light scatters

19. Angle of Incidence = Angle of Reflection
The Law of Reflection:
Angle of Incidence = Angle of Reflection
Өi = Өr
mirror
normal
Reflected ray
Incident ray өi өr

20. Constructive vs. Destructive Interference
When light waves interfere with each other, they effect the intensity (or brightness) of the light
Constructive: causes the light to get brighter
Destructive: causes the light to get dimmer

21. Diffraction Refers to the spreading or bending of waves around edges.
With light this causes interference patterns to be created.
Experiments called the single-slit and double-slit are used to show the interference patterns.

22. Single and Double Slit Experiments
The brighter areas are caused by constructive interference and the darker areas are caused by destructive interference.

23. Polarization
Light waves occur in many orientations and on multiple planes.
We can use polarizers to filter out directions we don’t want.

24. Polarization
By polarizing the light, we can change how the light looks and how much light can pass through a surface
Examples: