The Electromagnetic Spectrum Presented By: Isabelle Voler Shoaf, B1, 5/26/11

Anatomy of an Electromagnetic Wave Electromagnetic waves are formed when an electric field combines with a magnetic field at a perpendicular angle. The natural vibrations of these fields (which look something like a sin(x) equation) then interact and in doing so, induce each other to move.

The Electromagnetic Spectrum The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. These frequencies can range anywhere from zero Hz to 10^20 Hz and have been broken up into 8 categories of waves based on their sources and how they interact with matter.

EM Spectrum: Visual

Similarities and Differences in Waves All transverse waves All made up of photons All travel at the speed of light in a vacuum Differences Different frequencies and therefore wavelengths as well Differing sources Different interactions with matter

Radio Waves Source: radio waves are produced by an alternating current in a tuned electrical circuit. Use: communication technology, AM/FM radio, TV. Higher frequency radio waves can carry more information per time unit than lower ones and are used for TV’s whereas the low frequency radio waves are used for traditional radio stations.

Microwaves Source: Microwaves are produced by oscillations of electrons in a vacuum as well as when certain semi-conductors, such as water, get excited. Use: cell-phones, short-range internet links, cooking food, radar, and traffic cameras. They are known to cause cataracts as well.

Infrared Waves Source: Infrared waves are produced by a change in the rotational and vibrational kinetic energies of electrons in the atoms of heated bodies. Use: remote controls, night vision technology, and weather forecasting, and to capture images of far away objects in space.

Visible Light Source: Visible light can be generated by the re-arrangement of outer orbital electrons in molecules, when electrons emit light and other forms of electromagnetic radiation as they lose energy. Visible light is detected by stimulating the nerve endings of the retina of the human eye and with rods and cones. Use: TO SEE!!

Ultraviolet (UV) Waves Source: high energy electron transitions, and our sun. Use: production of vitamin D and melanin (tanning pigment in skin), to ionize atoms and kill bacteria. These waves can cause some items to fluoresce and give you skin cancer.

X-Rays Source: the rapid deceleration of fast moving electrons upon striking a metal target or by the sudden change in energy of the innermost orbital electrons in atoms. X-rays are also given off by stars. X-Rays have a relatively high penetrating power that increases as the density of the object its attempting to penetrate decreases (an inverse relationship) and increases as the frequency of the X-ray increases toward the Gamma end of the spectrum (a direct relationship). Use: In the medical field to see inside of people’s bodies, in airport security systems, and to detect objects far-away in outer space that emit X-Rays but are too far away to be seen with visible light.

Gamma Rays Source: Gamma Rays are produced by objects in outer space such as supernova explosions and regions around black holes. On Earth they are the result of radioactive decay and nuclear explosions. Use: to kill targeted cancerous cells in “Radiotherapy.”

Conclusion How to remember it all… Radio: Rabbits Micro: Mate Infrared: In Visual: Very UV: Unusual X-Ray: eXotic Gamma: Gardens