Watch video first- Science of Light &t=Light-Optics

Wave Description of Light  Electromagnetic radiation is light  A form of energy that exhibits wavelike behavior as it travels through space  Electromagnetic radiation consists of visible light, X rays, ultraviolet and infrared light, microwaves, and radio waves Look at this

Electromagnetic Spectrum  Shows all the forms of electromagnetic radiation  Light moves at constant rate in a Vacuum at 3x10^8 m/s That’s fast !!!! Watch This- Electromagnetic Spectrum asset/phy03_vid_nasaspectrum/

Electromagnetic Spectrum

Parts of Electromagnetic Spectrum in Order  Radio waves These waves are used to bring you the tunes from your favorite radio station, but they are also a type of radiation from the Sun with long wavelengths. Radio waves do more than just bring music to your radio. They also carry signals for your television and cellular phones. Don’t forget!! They have the longest wavelengths!

 Microwaves Microwaves have a slightly smaller wavelength than radio waves. Microwaves can be used to study the Universe, communicate with satellites, and cook popcorn. Because microwaves can penetrate haze, light rain and snow, clouds and smoke, these waves are good for viewing the Earth from space.

 Infrared radiation Infrared radiation has wavelengths longer than visible radiation and shorter than microwave radiation. Instruments on satellites that detect plants, rock types, and characteristics of the atmosphere use infrared radiation. The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared. The image at the left (courtesy of SE-IR Corporation, Goleta, CA) shows a cat in the infrared. The orange areas are the warmest and the white-blue areas are the coldest. This image gives us a different view of a familiar animal as well as information that we could not get from a visible light picture.

 Visible radiation This is the part of the electromagnetic spectrum that humans are able to see. It includes all of the colors of the rainbow which, when combined, make white light. Within the spectrum of visible light, red light travels in long waves while violet light travels in smaller waves Try this!!! All you need is a flashlight and a glass prim. Shine the light on the prism in a dark room in front of white paper. See what happens.

 Ultraviolet radiation With slightly more energy than the violet end of the visible light spectrum, most ultraviolet radiation (UV) from the Sun is blocked by Earth's atmosphere, but some makes it through. UV radiation helps plants grow and humans make vitamin D in their bodies. However, too much UV can cause sunburns, skin cancer, cataracts, and can damage plants too. Though these waves are invisible to the human eye, some insects, like bumblebees, can see them!

 X-ray radiation Because x-rays have short wavelengths and more energy than visible light, they travel through skin, tissue and organs but bounce off hard bone. That's how doctors use them to take photographs of bones. X-rays were first observed and documented in 1895 by Wilhelm Conrad Roentgen, a German scientist who found them quite by accident when experimenting with vacuum tubes. A week later, he took an X-ray photograph of his wife's hand which clearly revealed her wedding ring and her bones.

 Gamma-ray radiation Gamma rays have the shortest wavelengths and the most energy of all types of radiation! If you could see gamma-rays, the night sky would look strange and unfamiliar. The gamma-ray moon just looks like a round blob - lunar features are not visible. In high-energy gamma rays, the Moon is actually brighter than the quiet Sun. This image was taken by EGRET.

Wavelength  The distance between corresponding points on adjacent waves  Units for wavelength are usually meter, centimeter, or nanometer

Frequency (V)  Defined as the number of waves that pass a given point in a specific time, usually one second.  Expressed as waves per second  One wave/second is a hertz (Hz) named for Heinrich Heinz

Frequency and Wavelength  Mathematically related

Comparing the frequencies

COLORS ROYGBIV R=red O=orange Y=yellow G=green B=blue I=Indigo V=Violet The colors of light happen to be the only wavelengths that our eyes can see

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