1. Electromagnectic Spectrum

2. Electromagnetic Spectrum
In 1852, James Clerk Maxwell proved that visible light was part of a larger spectrum.
Each color of visible light is a different wavelength of electromagnetic radiation.
Humans can see radiation from Red (longest) through to Violet (shortest).
Visible light is only a small part of the Electromagnetic Spectrum.
Lucky for us, most of the invisible radiation can not pass through our atmosphere.

3. Nature of Electromagnetic Waves
They are Transverse waves without a medium. (They can travel through empty space)
They travel as vibrations in electrical and magnetic fields.
Speed of electromagnetic waves = 300,000,000 meters/second-

4. Waves of the Electromagnetic Spectrum
Ultraviolet
Rays
Gamma Rays
Radio Waves
Infrared Rays
Visible Light
X-Rays
Microwaves

5. RADIO WAVES
A. Have the longest wavelengths and lowest frequencies of all the electromagnetic waves.
B. A radio picks up radio waves through an antenna and converts it to sound waves.
C. Each radio station in an area broadcasts at a different frequency. # on radio dial tells frequency.
D. MRI (MAGNETIC RESONACE IMAGING)
Uses Short wave radio waves with a magnet to create an image

6. MRI of the Brain

7. Amplitude modulation (AM) waves bounce off ionosphere that is how you can pick up stations from different cities.
(535kHz-1605kHz= vibrate at 535 to 1605 thousand times/second)

8. Frequency modulation (FM)—waves travel in a straight line & through the ionosphere—you lose reception when you travel out of range.
(88MHz-108MHz = vibrate at 88million to 108million times/second)

9. Examples

10. MICROWAVES
Microwaves—have the shortest wavelengths and the highest frequency of the radio waves.
Used in microwave ovens.
Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food.
Used by cell phones and pagers.
RADAR (Radio Detection and Ranging)
Used to find the speed of an object by sending out radio waves and measuring the time it takes them to return.

11. MICROWAVES
Magellan Beginning in 1990 and continuing until 1993, the Magellan spacecraft mapped the surface of Venus using radar ranging.
To get around the problem of the dense cloud layer, Magellan viewed the surface of Venus using microwave radiation. Microwave radiation is a type of light with longer wavelength than visible light. Microwave radiation is able to penetrate the cloud layer of Venus.

12. INFRARED RAYS Infrared= below red
Shorter wavelength and higher frequency than microwaves.
You can feel the longest ones as warmth on your skin
Heat lamps give off infrared waves.
Warm objects give off more heat energy than cool objects.
Thermogram—a picture that shows regions of different temperatures in the body. Temperatures are calculated by the amount of infrared radiation given off. Therefore people give off infrared rays.

13. Digital Infrared Thermal Imaging
Using UV radiation

14. VISIBLE LIGHT
Shorter wavelength and higher frequency than infrared rays.
Electromagnetic waves we can see.
Longest wavelength= red light
Shortest wavelength= violet (purple) light
When light enters a new medium it bends (refracts). Each wavelength bends a different amount allowing white light to separate into it’s various colors ROYGBIV.

15. The visible light spectrum ranges from short-wavelength violet to long-wavelength red. Photons of light from violet end of the spectrum have the highest energies and the highest frequencies, while red photons have lower energies and lower frequencies.

16. ULTRAVIOLET RAYS
Shorter wavelength and higher frequency than visible light
Carry more energy than visible light
Used to kill bacteria. (Sterilization of equipment)
Causes your skin to produce vitamin D (good for teeth and bones)

17. Used to treat jaundice
( in some new born babies.)
Too much can cause skin cancer.
Use sun block to
protect against (UV rays)

18. ULTRAVIOLET RAYS
We see this flower in normal light, but the main pollinators of this flower, like bees, see the flower in UV light.

19. X- RAYS Shorter wavelength and higher frequency than UV-rays
Carry a great amount of energy
Can penetrate most matter.
Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)
Too much exposure can cause cancer
(lead vest at dentist protects organs from unnecessary exposure)
Used by engineers to check for tiny cracks in structures.
The rays pass through the cracks and the cracks appear dark on film.

20. X- RAYS

21. GAMMA RAYS Shorter wavelength and higher frequency than X-rays
Carry the greatest amount of energy and penetrate the most.
Used in radiation treatment to kill cancer cells.
Can be very harmful if not used correctly.

22. GAMMA RAYS

23. SUMMARY
A. All electromagnetic waves travel at the same speed. (300,000,000 meters/second in a vacuum.
B. They all have different wavelength and different frequencies.
Long wavelength-lowest frequency
Short wavelength highest frequency
The higher the frequency the higher the energy.