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| Radiation
is all around us. Did you know that your TV gives off electromagnetic
radiation? The radiation created by your microwave pops your popcorn.
The light from the sun and the light bulbs in your classroom also
produce electromagnetic radiation. Try this idea on for size: “Radiation” and “electromagnetic energy” is one and the same thing. We use these two ways to describe radiation interchangeably in this essay. What is Radiation? Radiation is electromagnetic energy in transit! All forms of radiation are part of what scientists call the electromagnetic spectrum. The electromagnetic spectrum includes radio waves, TV waves, microwaves, visible light, ultraviolet light, X-rays, and gamma rays. The radiation in the electromagnetic spectrum is created by many different energy sources, but each type of radiation shares two characteristics: • Wavelength: We can picture a wave’s length in our minds if we imagine the waves in the ocean. • Frequency: Frequency is the number of waves that hit the side of a boat in a given period of time. The wavelength of a radio wave is 300 km long or about 186 miles. Visual light has a slightly longer wavelength than microwaves, and a microwave can be measured in centimeters. Gamma rays, the shortest waves, and very dangerous to humans, are infinitesimal in comparison. Because all electromagnetic waves travel at the speed of light, a column of light 300,000 km long enter your eyes every second. Fewer radio waves (which we cannot see because our eyes do not detect radio waves) would enter our eyes than, say, waves of red light, because the wavelength of the radio waves is much longer in length. When you look at a red ball, two hundred thousand billion (200,000,000,000,000) ripples of red light enter your eyes every second. Radiation is Energy: Long Wavelength + Low Frequency = Low Energy Long wavelength-low frequency radiation has lower energy. For example, radio waves have the longest wavelength and lowest frequencies; therefore, they have the lowest amount of energy of all forms of radiation. X-rays and gamma rays have the shortest wavelengths and the highest frequencies. They have tremendous energy. The more energy the form of radiation has the more potential it has to be dangerous to humans. Two Types of Radiation: Nonionizing and Ionizing Ion – The word “ion” refers to atoms and their electrons. Low-energy radiation cannot change an atoms structure. It is nonionizing. High-energy radiation can penetrate and change an atom’s structure. It is ionizing. Scientists divide radiation into two types: nonionizing radiation and ionizing radiation. Non-Ionizing Radiation – The First Type Nonionizing radiation is low energy radiation. It is produced by both manmade and natural sources and is harmless in low doses. Twenty percent of the radiation we are exposed to every day comes man-made objects. Examples of man-made, nonionizing radiation are the light from a light bulb, TV,and radio waves. Other sources of nonionizing radiation include the smoke detectors in your home and a computer’s monitor. One form of manmade, nonionizing radiation, microwaves, is a dangerous exception. It is low energy and will not ionize atoms, but its frequency and wavelength produce just the right level of energy to cause harmonic vibrations in water. Microwaves heat water. Microwaves are dangerous to humans because are bodies are 98 percent water! The other eighty percent of the nonionizing radiation that we are exposed to on Earth comes from natural sources. This type of radiation is also known as “background radiation.” Examples of background radiation are sunlight and the low-frequency radiation given off by certain types of rocks. For instance, people living in the Rocky Mountains are exposed to radiation from trace levels of uranium. Even the soil in our yards gives off some forms of low level, nonionizing radiation. Humans need some forms of nonionizing radiation just to survive. All living things require light and heat. Even though most nonionizing radiation is harmless (except microwaves), we have learned that too much ultraviolet radiation can be dangerous to human health. Ultraviolet radiation is what causes sun burn and, possibly, skin cancers. Ionizing Radiation – The Second Type The other type of radiation is called ionizing radiation. Examples of ionizing radiation are x-rays and gamma rays. On Earth, man produces and tries to harness ionizing radiation to run nuclear power plants, to explore the nature of the atom in the laboratory, and to conduct medical treatments of some types of cancer and other diseases. In space, the space station is constantly bombarded by ionizing radiation. On Earth we are protected from the high-energy radiation of space by the Earth’s magnetic field and atmosphere. Sources of radiation on the space station are galactic cosmic rays, trapped radiation in the Van Allen Belts, and solar proton events. These sources of radiation are of great concern to the astronauts. Ionizing radiation, such as x-rays and gamma rays, has short wavelengths. Therefore it has high frequencies. These forms of radiation are dangerous to humans. Their high energy permits them, not only to penetrate an atom, but also to penetrate our skin and the nucleus of any cell in the human body. Because of the damage that can be caused to the bodies of the astronauts by the radiation produced by radiation in space, and particularly by the incredibly high levels of radiation produced by the energy in a solar proton event, Mission Control and our specialist teams have to monitor and measure high-energy radiation with devices found on the space station. |
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