1. Electromagnetic (EM) waves are invisible forms of energy that travel though the universe

2. Electromagnetic Waves
Why are they called electromagnetic?
Electromagnetic waves are formed when an electric field (which is shown in red arrows) couples with a magnetic field (which is shown in blue arrows).

3. Types of EM Waves All EM waves fall into one of the following types:
+Radio Waves
+Micro Waves
+Infrared Waves
+Visible Light Waves
+Ultra Violet Waves
+X-Ray Waves
+Gamma Ray Waves
104
10-4
10-2 1
102
10-12
10-10
10-8
10-6
Wavelength 
(m)
108
106
1012
1014
1010
1018
1020
1016
Frequency
(Hertz)
Radio & Television
Radar
Infra Red
Ultra
Violet
x-Rays
Gamma Rays
AM Radio
FM Radio
Television
Orange
Red
Yellow
Green
Blue
High Energy
Low Energy

4. Waves in the electromagnetic spectrum vary in size from long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom.

5. Radio waves Longest wavelength EM waves Uses: TV broadcasting
AM and FM broadcast radio
Avalanche beacons
Heart rate monitors
Cell phone communication
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

6. Microwaves Wavelengths from 1 mm- 1 m Uses: Microwave ovens
Bluetooth headsets
Broadband Wireless Internet
Radar
GPS
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

7. Infrared Radiation Wavelengths in between microwaves and visible light
Uses:
Night vision goggles
Remote controls
Heat-seeking missiles
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

8. Visible light
Only type of EM wave able to be detected by the human eye
Violet is the highest frequency light
Red light is the lowest frequency light
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

9. Isaac Newton was the first to figure out that white light can be separated into the visible full spectra of colors because different wavelengths of light travel at different speeds when going from one medium to another

10. Ultraviolet Shorter wavelengths than visible light Uses: Black lights
Sterilizing medical equipment
Water disinfection
Security images on money
There is one more UV slide…

11. X-rays Tiny wavelength, high energy waves Uses: Medical imaging
Airport security
Inspecting industrial welds
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

12. Gamma Rays Smallest wavelengths, highest energy EM waves Uses
Food irradiation
Cancer treatment
Treating wood flooring
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

13. Temperature and the EM Spectrum
Shorter wavelengths of the EM spectrum have higher temperatures

14. Wave Properties
The main properties of a wave can be defined using the following vocabulary:
Frequency
Wavelength
Amplitude
Speed

15. Frequency
Frequency is defined as the number of waves that pass a certain point in a second.(waves per second)

16. This is a shorter wavelength This is a longer wavelength
Wavelength is defined as the distance from the crest of one wave to the crest of the next. (Also called the wave period)
This is a shorter wavelength
This is a longer wavelength

17. Wavelength Notice the wavelength is
long (Radio waves) and gets shorter (Gamma Rays)

18. Amplitude
Amplitude Is the height of the wave and it is reflective of the power of a wave
Both of the waves below have the same wavelength but the one on the right has the greater amplitude
Amplitude
An audio amplifier amplifies the strength of the electrical signal which then amplifies the height of the sound wave making a louder sound. ROCK ON!

19. Speed of an EM wave
Speed of a wave is calculated by multiplying the frequency x wavelength
The speed of the electromagnetic spectrum is the speed of light
Speed of light = 3x108 m/s or 186,000 miles/second

20. Stars & EM Waves
When stars go through the process of nuclear fusion, EM waves are created and the energy is released as a photon of light
All of the EM waves produced by stars are invisible to us accept visible light
A photon is a little packet of light energy that behaves as a wave and a particle

21. The Sun at Different Wavelengths
Visible
Ultraviolet
Radio
X-ray

23. Electromagnetic radiation from space is unable to reach the surface of the Earth except at a very few wavelengths, such as the visible spectrum, radio frequencies, and some ultraviolet wavelengths.

25. Clicking the little rainbow box at the top of each slide will bring you back to this one

26. EM Spectrum Video (5 min)

28. EM Waves as a Tool for Astronomers
There are 3 main types of visible spectrums that can tell us what elements objects are made up of:
Continuous spectrum
Continuous Spectrum – White light producing Full ROYGBV spectra

29. Emission or bright line spectrum
Bright Line Spectrum – the spectrum of an element heated to a temperature where it glows and produces light (incandescent) and appearing as one or more bright lines.
(Like fingerprints, all elements have a unique signature of lines)

30. Absorption or dark line spectrum
Absorption Spectrum – When white light passes through ionized gas or vapor the wavelength of the gasses elemental composition is absorbed and the rest passes through to the observer

31. The outer layers of a star are nothing more then hot gas.

32. How are the absorption and emission lines similar and different?

33. Hydrogen Absorption (Dark Line) & Emission (Bright Line) Spectra

34. How do we interpret an actual spectrum?
By carefully studying the features in a spectrum, we can learn a great deal about the object that created it.

35. What is this object?
Reflected Sunlight: Continuous spectrum of visible light is like the Sun’s except that some of the blue light has been absorbed - object must look red

36. What is this object?
Thermal Radiation: Infrared spectrum peaks at a wavelength corresponding to a temperature of 225 K

37. What is this object?
Carbon Dioxide: Absorption lines are the fingerprint of CO2 in the atmosphere

38. What is this object?
Ultraviolet Emission Lines: Indicate a hot upper atmosphere

39. What is this object?
Mars!

40. Doppler Effect- the change in frequency of a wave for an observer moving relative to its source.
This effect can be heard with sound waves The noise of a passing siren falls in pitch as it passes. This is due to the stretching of the sound waves behind the vehicle and the compression of sound wavehe Doppler Effect.

41. Visible Spectrum Doppler Shift In Light
This effect can also be seen in the visible spectrum of light waves!
-The motion of an object traveling away from us produces a shift towards the red end of the spectrum of light due to a stretching of the light waves.
-The Motion of an object traveling toward us produces a shift towards the blue end of the spectrum of light due to compressing of the light waves.
-As a result, objects traveling towards us look more blue and objects traveling away from us look more red.
Red Orange Yellow Green Blue Indigo Violet
Visible Spectrum

42. Doppler effect of light can be remembered by thinking of a car heading towards or away from you.

43. This light source is moving away at 15,000 mile per hour
By measuring the amount that dark lines shift, scientists can calculate how fast objects are moving toward or away.
This light source is moving away at 15,000 mile per hour
This light source is moving away at 94,000 mile per hour
This light source is not moving away at all.

44. Reading a Spectrascope.
For this Bright Line Spectrum there are three lines.
a thick blue line at approximately 445
a green at approximately 525
A red line at approximately 635

45. Fluorescent light bulb Emission Spectrum
What frequency of waves are the 5 lines?

46. The Spectrum of the Sun

47. Emission (Bright Line) Spectra

48. Krypton Gas

49. Bright Line Spectrum
Hydrogen
Helium
Carbon
Nitrogen
Krypton