1. Electromagnetic Spectrum
Unit 3 Seminar

2. Electromagnetic Wave:
Is a wave that is made up of electrical and magnetic fields that fluctuate together
Electromagnetic waves are generated any time a charged object is accelerated
Image combing your hair on a dry winter day when the comb picks up static charge.
J.Trefil and R. Hazen, The Sciences, 2011, p.126

3. Electromagnetic Spectrum:
The entire array of waves, varying in frequency & wavelength,
but all resulting from an accelerating electrical charge
Electromagnetic waves transfer energy
What has been called radiation
Includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays,

4. Radio waves, visible light, nuclear radiation, and X-rays are also kinds of electromagnetic waves.

5. Look at the diagram and move from left to right and you will see that radio waves have the least energy and gamma rays from nuclear sources have the most energy.

6. Microwaves:
Has wavelengths ranging from approximately 1 meter to 1 millimeter
Microwaves are good for transmitting information from one place to another because microwave energy can penetrate haze, light rain and snow, clouds, and smoke.
Used for cooking

7. Microwave Ovens
A special electronic device accelerates electrons rapidly & produces microwave radiation which carries energy
The microwaves are guided into the main cavity of the oven
Thus the wave energy remains inside the box until its absorbed by something,
usually by water molecules that get hot from the absorbed energy.

8. Radiation The transfer of heat by electromagnetic radiation
Radiation is the only kind of energy that can travel through the emptiness of space
Doesn’t require any medium to move heat
Can travel through a vacuum
The energy that falls on Earth in the form of sunlight is in the form of radiation
J.Trefil and R. Hazen, The Sciences, 2011, p.81

9. Radio waves have the least energy and gamma rays from nuclear sources have the most energy

10. Your cousin Pauline, once a proud microwave chef, has taken to dining out a lot more often and using her toaster oven for the leftovers.
She recently learned of the dangers of radiation, thanks to rising awareness of the dangers of tanning booths and even recent disasters at nuclear power plants, and is concerned that her microwave could pose a threat to her own health.

11. What should Pauline know about these different forms of radiation?
Which forms are dangerous and why?
Can you convince her to return to her microwaving ways?

12. Infrared Radiation
Wavelengths of electromagnetic radiation that extend from a millimeter to a micron
Felt as heat radiation
All warm objects emit infrared radiation
Our skin absorbs radiation and provides a kind of detector
J.Trefil and R. Hazen, The Sciences, 2011, p.133

13. The red-orange areas are the warmest and the white-blue areas are the coldest. .

14. In an attempt to show Pauline there are even more forms of electromagnetic radiation which are not only harmless but actually helpful,
you ask if she has ever experienced infra-red light treatments at the chiropractor or is aware of the medical uses for infra-red imagery.
How does infra-red radiation differs from that used for X-ray imaging?

16. What are some of the controversies concerning the dangers of extremely low-frequency (ELF) radiation?
Based upon the reading and your own experience, do you think this is a topic you should discuss with your cousin Pauline?

17.
ScienceCasts: Mysterious Objects at the Edge of the Electromagnetic Spectrum