Electromagnetic Spectrum: Notes in order of lowest frequencies to highest frequencies

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Electromagnetic Spectrum Radio Waves Microwaves Infrared Rays Visible Light Ultraviolet Rays X Rays Gamma Rays

Radio Waves Longest wavelengths Lowest frequencies Broadcast waves: carry signals for both radio and television programs. This includes transforming into electrical signals in a radio or pictures and sounds for a TV.

Microwaves The radio waves with the shortest wavelengths and highest frequencies. Microwave ovens cook and heat your food. Also used in cellular phone communications and radar. Radar: radio detection and ranging. A radar is a system that uses reflected radio waves to detect objects and measure their distance and speed.

Infrared Rays The invisible heat you feel in infrared radiation or infrared rays. Have shorter wavelengths and higher frequency than radio waves so they have more energy. Often called heat rays because you feel infrared rays as heat. Most objects give off some infrared rays.

Warmer objects give off infrared waves with more energy and higher frequencies than cooler objects. A thermogram is an image that shows region of different temperatures in different colors.

Infrared cameras are used to see objects in the dark Infrared cameras are used to see objects in the dark.(Firefighters use them to locate victims inside dark or smoky building) Satellites in space use infrared cameras to study the growth of plants and the motions of clouds.

Visible Light Electromagnetic waves that you can see. Shorter wavelengths and higher frequencies than infrared rays. The longest wavelength appear red in color.

Visible light that appears white is actually a mixture of many colors. White light from the sun can be separated by a prism into the colors of the visible spectrum(ROYGBIV) Red light waves refract the least and Violet light waves refract the most.

Ultraviolet Rays Have higher frequencies than visible light. Carry more energy. This energy is great enough to damage or kill living cells. Small doses of UV rays are useful. They can cause skin cells to produce Vitamin D. To much exposure can be harmful: burn your skin, cause skin cancer, and damage your eyes.

X Rays Carry more energy than UV rays and can penetrate most matter. Dense matter, such as bone or lead, absorbs X-rays and does not allow them to pass through. Used to make images of bones inside the body or teeth.

To much exposure can cause cancer. Dentist use lead aprons to absorb x-rays from reaching your body. Sometimes used in industry and engineering to examine the internal structure of buildings.

Gamma Rays Shortest wavelengths Highest frequencies Most penetrating of all electromagnetic waves. Produced by some radioactive substances and certain nuclear reactions.

Have some medical uses: can be used diagnose and kill cancer cells inside the body. Some objects in space, such as explosions of stars, give off burst of gamma rays but they are blocked by the Earth’s atmosphere.