1. Light Interactions

2. What is light? Light is an electromagnetic (EM) wave.
An EM wave is a wave that consists of changing electric and magnetic fields.
EM waves require no matter through which to travel.
EM waves can be produced by the vibration of charged particles.
The speed of light in a vacuum is about 300,000,000 m/s.
EM waves from the sun are the major source of energy for Earth.

3. The Electromagnetic Spectrum
All electromagnetic (EM) waves travel at the speed of light. EM waves differ only by wavelength and frequency.
The entire range of EM waves is called the electromagnetic spectrum.

4. Radio waves are used for communication.
AM means amplitude modulation
FM means frequency modulation
PhET Simulation

5. Microwaves are used in cooking and in radar.
PhET Simulation

6. The absorption of infrared waves is felt as an increase in temperature.

7. Visible Light
Visible light is the narrow range of wavelengths that humans can see.
Different wavelengths are seen as different colors.

8. Ultraviolet Light Killing bacteria Producing vitamin C
Can cause sunburns

9. Bees see UV light…
So they see the world differently than we do!

10. X-Rays

11. Gamma Rays

12. Light Interactions
The law of reflection states that the angle of incidence is equal to the angle of reflection.
Things that are luminous can be seen because they produce their own light.
Things that are illuminated can be seen because light reflects off them.
Absorption is the transfer of light energy to particles of matter.
Scattering is an interaction of light with matter that causes light to change direction.

13. Light Interactions
Refraction of light waves can create optical illusions and can separate white light into separate colors.
Diffraction depends on the light’s wavelength.
Light waves diffract more when traveling through a narrow opening.
Interference can be constructive or destructive.
Interference of light waves can cause bright and dark bands.

14. Law of Reflection: angle of incidence = the angle of reflection

16. Absorption & Scattering

17. Refraction

18. Refraction

19. Diffraction & Interference

20. Do You See What I See?

21. March 27, 2015 Do Now: Angles of Reflection (share protractors)
Take out HW
No homework tonight 

22. Light & Color
Objects are transparent, translucent, or opaque depending on their ability to transmit light.
Colors of opaque objects are determined by the color of light that they reflect.
Colors of translucent and transparent objects are determined by the color of light they transmit.
White light is a mixture of all colors of light.
Light combines by color addition. The primary colors of light are red, blue, and green.
Pigments give objects color. Pigments combine by color subtraction. The primary pigments are magenta, cyan, and yellow.

23. Objects are transparent, translucent, or opaque depending on their ability to transmit light.

24. Colors of opaque objects are determined by the color of light that they reflect.

25. Colors of translucent and transparent objects are determined by the color of light they transmit.

26. Light combines by color addition
Light combines by color addition The primary colors of light are red, blue, and green.

27. Pigments combine by color subtraction.

28. The primary pigments are magenta, cyan, and yellow.

29. Question 1
Ultraviolet light has a higher frequency than infrared light has. Which statement about visible light is true?
Blue light has a longer wavelength than orange light has.
Green light has a higher frequency than violet light has.
Yellow light has a shorter wavelength than blue light has.
Red light has a lower frequency than green light has.

30. Question 1
Ultraviolet light has a higher frequency than infrared light has. Which statement about visible light is true?
Blue light has a longer wavelength than orange light has.
Green light has a higher frequency than violet light has.
Yellow light has a shorter wavelength than blue light has.
Red light has a lower frequency than green light has.

31. Question 2
Which light interaction explains why you can see things that do not produce their own light?
absorption
reflection
refraction
diffraction

32. Question 2
Which light interaction explains why you can see things that do not produce their own light?
absorption
reflection
refraction
diffraction

33. Question 3 Which electromagnetic waves is the eye able to see?
Red, green, and ultraviolet
Red, infrared, and yellow
Blue, green, and ultraviolet
Orange, green, and red

34. Question 3 Which electromagnetic waves is the eye able to see?
Red, green, and ultraviolet
Red, infrared, and yellow
Blue, green, and ultraviolet
Orange, green, and red