1. Electromagnetic Waves
Chapter 18
Electromagnetic Waves

2. Electromagnetic Waves
Transverse waves consisting of changing electric & magnetic fields

3. Electromagnetic Waves
Carry energy

4. Electromagnetic Waves
Do not need a medium (can travel through empty space or through matter)
Called electromagnetic radiation

5. Represented by c 3.00 x 108 m/s 300,000,000 m/s
Speed of Light
Represented by c
3.00 x 108 m/s
300,000,000 m/s
Recorded in 1926 by Albert Michelson

6. Speed of Electromagnetic Waves
Wavelength x frequency= speed
Wavelength and frequency are inversely proportional (as one goes up the other goes down)
Speed is a constant (3.00 x 108 m/s)
You will solve for either wavelength or frequency

7. Speed of Electromagnetic Waves
Frequency =
speed ÷ wavelength
Wavelength =
speed ÷ frequency

8. Intensity
Photons (light particles) travel outward from a light source in all directions
Intensity decreases as photons travel farther from the source
Intensity is the rate at which a wave’s energy flows through a given unit of area

9. Electromagnetic Spectrum
Radio waves
Infrared rays
Visible light
Ultraviolet rays
X-rays
Gamma rays

10. Electromagnetic Spectrum

11. Electromagnetic Spectrum

12. Longest wavelengths Lowest frequencies
Radio Waves
Longest wavelengths
Lowest frequencies
Used in radio & TV, microwaves, and radar.

13. Can be seen by the human eye
Visible Light
Can be seen by the human eye
Each wavelength has a specific frequency and a particular color

14. Visible Light
From highest wavelength & lowest frequency to lowest wavelength & highest frequency
Red
Orange
Yellow
Green
Blue
Indigo
Violet
ROY G BIV= way to remember

15. Ultraviolet Rays Higher frequencies than violet light
Helps you skin produce vitamin D in moderation
Excess causes sunburn, wrinkles, and skin cancer
Kills microorganisms
Used in plant nurseries during the winter
Can cause eye damage

16. X-rays Can penetrate matter that light cannot
In medicine-soft tissue looks dark, bones appear white
Excess can kill tissue
Used to inspect seals on cans
Used to identify contents of large trucks, packages, and suitcases.

17. Gamma Rays Shortest wavelengths Highest frequencies Most energy
Greatest penetration
Overexposure is deadly
Kills cancer cells
Used to create images of the brain and to inspect pipelines

18. Chapter 18 Part 2
Light

19. Depends on what the object the light hits is made of
Light Behavior
Depends on what the object the light hits is made of

20. Materials
Transparent
Translucent
Opaque

21. You can see through this.
Transparent Material
You can see through this.
Transmits light- allows light to pass through it

22. You can see through this but it is blurry. Scatters light
Translucent Material
You can see through this but it is blurry.
Scatters light

23. You cannot see through this. Absorbs or reflects all light
Opaque Material
You cannot see through this.
Absorbs or reflects all light

24. Light Interactions
When light strikes a new medium, the light can be reflected, absorbed, or transmitted.

25. Light Interactions
When light is transmitted, it can be refracted, polarized, or scattered.

26. Can be regular or diffuse
Reflection
Can be regular or diffuse

27. Regular Reflection
Parallel light waves hit a smooth surface and all reflect in the same direction

28. Diffuse Reflection
Parallel light waves hit a rough surface and reflect in many different directions

29. Causes mirages- false/distorted images
Refraction
Light waves are bent
Causes mirages- false/distorted images

30. Polarization Light waves that only vibrate in one plane
Polarizing filters can polarize light

31. Polarization

32. Polarization
Vertical filters block horizontal light waves and vice versa.

33. Polarization

34. Light is redirected when it passes through a medium
Scattering
Light is redirected when it passes through a medium

35. Scattering Causes the red sky at sunrise/sunset
Blue light has a shorter wavelength than red and is scattered more easily
Without the blue, we see red.

36. Made up of all colors in the visible spectrum
White Light
Made up of all colors in the visible spectrum

37. When white light is broken into separate colors Caused by a prism
Dispersion
When white light is broken into separate colors
Caused by a prism

38. Dispersion In the prism
Longer wavelengths (like red) are bent the least
Shorter wavelengths (like violet) are bent the most

39. Color
The color of any object depends on what the object is made of and on the color of light that strikes the object.

40. Color
The color that we see is the color of light that an object does not absorb.

41. Color
The car below is absorbing all wavelengths of light except blue.

42. White- all light is reflected Black- all light is absorbed
Black and White
White- all light is reflected
Black- all light is absorbed

43. Primary Colors Red Blue Green
All other color combinations are created by reflections of these three.