By: Debra Ronca. Say the word "radiation" to three different people, and you'll probably get three different reactions. Your aunt may tell you how radiation destroyed her cancer. Your neighbor might mention the "duck and cover" procedures of his day. And your comics-loving friend will explain how gamma rays turned Bruce Banner into The Hulk.
Sometimes it's dangerous; sometimes it's not. Radiation is both natural and man-made. Our bodies are exposed to natural radiation every day -- from soil and underground gases to cosmic radiation from the sun and outer space. We're also exposed to radiation from our own inventions -- medical procedures, televisions , cell phones and microwave ovens. Radiation isn't necessarily always dangerous. It depends on its strength, type and the length of exposure.
Most people will tell you Marie Curie discovered radiation, along with her husband and research partner Pierre. And that's right -- sort of.
Curie actually discovered the element radium in , an accomplishment that would make her the first female recipient of the Nobel Prize. Radiation is energy that travels in the form of waves electromagnetic radiation or high-speed particles particulate radiation. Particulate radiation happens when an unstable or radioactive atom disintegrates. Electromagnetic EM radiation , on the other hand, has no mass and travels in waves. EM radiation can range from very low energy to very high energy, and we call this span the electromagnetic spectrum.
Within the EM spectrum, there are two types of radiation -- ionizing and non-ionizing. In the late s, both Marie and her husband Pierre began suffering various ailments. Marie suffered several cataracts now a known side effect of radiation and eventually succumbed to anemia related to radiation in her bone marrow. Electromagnetic EM radiation is a stream of photons, traveling in waves. The photon is the base particle for all forms of EM radiation.
But what's a photon? It's a bundle of energy -- of light -- always in motion. In fact, the amount of energy a photon carries makes it sometimes behave like a wave and sometimes like a particle. Scientists call this wave-particle duality. Low-energy photons such as radio behave like waves, while high-energy photons such as X-rays behave more like particles. You can read more about how photons work in How Florescent Lamps Work. EM radiation can travel through empty space.
This differentiates it from other types of waves, such as sound, which need a medium to move through. The higher the energy, the stronger, and therefore more dangerous, the radiation. The only difference between a radio wave and a gamma ray is the energy level of the photons [source: NASA ]. Below is the electromagnetic spectrum at a glance. Radio : Radio waves have the longest wavelength in the electromagnetic spectrum up to a football field long.
They are invisible to our eyes. They bring music to our radios, sound and picture to our televisions , and carry signals to our cell phones. Cell phone waves are shorter than radio waves, but longer than microwaves. Microwaves : Also invisible, we use microwaves to heat our food quickly.
Telecommunications satellites use microwaves to transmit voice through the phone. Microwave energy can penetrate haze, clouds or smoke, and thus is useful for transmitting information.
Some microwaves are used for radar , like the Doppler radar your weatherman uses on the news. The entire universe has faint cosmic microwave background radiation -- something scientists connect to the Big Bang Theory. Infrared : Infrared lies between the visible and invisible portions of the EM spectrum. Your remote control uses infrared light to change the channel. We feel infrared radiation every day via the sun's heat. Infrared photography can detect temperature differences.
Snakes can actually detect infrared radiation, which is how they are able to locate warm-blooded prey in total darkness. Visible : This is the only part of the electromagnetic spectrum we can see. We see the different wavelengths in this band of the spectrum as the colors of the rainbow. The sun , for example, is a natural source of visible waves.
When looking at an object, our eyes see the color of light reflected, and all other colors are absorbed. Ultraviolet : Ultraviolet UV rays are what cause us to become sunburned. Humans can't see UV rays, but some insects can. Our atmosphere's ozone layer blocks most UV rays. However, as our ozone layer depletes due to use of chlorofluorocarbons CFCs , UV levels are increasing.
This can lead to health effects like skin cancer [source: EPA ]. X-rays : X-rays are very high-energy light waves. We're most familiar with their use in a doctor's office, but X-rays also naturally occur in space. But don't worry, X-rays can't penetrate from outer space to the Earth's surface. Read more in How X-rays Work.
Gamma rays : Gamma rays have the most energy and shortest wavelength of the entire spectrum. Nuclear explosions and radioactive atoms generate these rays. Gamma rays can kill living cells , and medical professionals sometimes use them to destroy cancerous cells. In deep space, gamma ray bursts occur daily, but their origins are still a mystery.
However, from the s to s, shoe sales clerks actually used an X-ray machine for shoe fitting. Although there were no reported overexposure injuries to customers, employees weren't so lucky. One shoe model suffered enough complications from X-ray overexposure to require amputation of her entire leg [source: Frame ]. Radiation is broken down into two types: non-ionizing and ionizing. On the electromagnetic EM spectrum, this break occurs between infrared and ultraviolet. Drilling down further, ionizing radiation comes in three main types: alpha particles, beta particles and gamma rays.
We'll discuss these types of radiation in more detail later in this article. Non-ionizing radiation is relatively low-energy radiation that doesn't have enough energy to ionize atoms or molecules. It's located at the low end of the electromagnetic spectrum. Non-ionizing radiation sources include power lines, microwaves , radio waves, infrared radiation, visible light and lasers.
Although considered less dangerous than ionizing radiation, overexposure to non-ionizing radiation can cause health issues. Let's take a look at some examples of non-ionizing radiation and the safety issues surrounding them. Extremely low frequency ELF radiation is the radiation produced by things like power lines or electrical wiring. There are health concerns associated with magnetic field exposures near power lines, and this issue is very controversial.
Obviously, ELF radiation surrounds us every day, but hazardous exposure depends on the strength of the ELF at the source, as well as the distance and duration of exposure. Research on ELF radiation focuses on cancer and reproductive issues. There is no definitive link between ELF radiation and illness, but studies have shown some preliminary connections [source: WHO ]. The deuterium isotope of hydrogen is stable. A third isotope, hydrogen-3 also known as tritium , has one proton and two neutrons.
It turns out this isotope is unstable. That is, if you have a container full of tritium and come back in a million years, you will find that it has all turned into helium-3 two protons, one neutron , which is stable.
The process by which it turns into helium is called radioactive decay. Certain elements are naturally radioactive in all of their isotopes.
Uranium is the best example of such an element and is the heaviest naturally occurring radioactive element. There are eight other naturally radioactive elements: polonium, astatine, radon, francium, radium, actinium, thorium and protactinium. All other man-made elements heavier than uranium are radioactive as well. Americium, a radioactive element best known for its use in smoke detectors , is a good example of an element that undergoes alpha decay. An americium atom will spontaneously throw off an alpha particle.
An alpha particle is made up of two protons and two neutrons bound together, which is the equivalent of a helium-4 nucleus. In the process of emitting the alpha particle, the americium atom becomes a neptunium atom. If you were looking at an individual americium atom, it would be impossible to predict when it would throw off an alpha particle.
However, if you have a large collection of americium atoms, then the rate of decay becomes quite predictable.
For americium, it is known that half of the atoms decay in years. Therefore, years is the half-life of americium Every radioactive element has a different half-life, ranging from fractions of a second to millions of years, depending on the specific isotope.
For example, americium has a half-life of 7, years. Tritium hydrogen-3 is a good example of an element that undergoes beta decay. In beta decay, a neutron in the nucleus spontaneously turns into a proton, an electron, and a third particle called an antineutrino.
The nucleus ejects the electron and antineutrino, while the proton remains in the nucleus. The ejected electron is referred to as a beta particle. The nucleus loses one neutron and gains one proton. Therefore, a hydrogen-3 atom undergoing beta decay becomes a helium-3 atom.
In spontaneous fission , an atom actually splits instead of throwing off an alpha or beta particle. The word "fission" means "splitting. For example, one fermium atom may become a xenon and a palladium atom, and in the process it will eject four neutrons known as "prompt neutrons" because they are ejected at the moment of fission. These neutrons can be absorbed by other atoms and cause nuclear reactions, such as decay or fission, or they can collide with other atoms, like billiard balls, and cause gamma rays to be emitted.
Neutron radiation can be used to make nonradioactive atoms become radioactive; this has practical applications in nuclear medicine. Neutron radiation is also made from nuclear reactors in power plants and nuclear-powered ships and in particle accelerators, devices used to study subatomic physics.
In many cases, a nucleus that has undergone alpha decay, beta decay or spontaneous fission will be highly energetic and therefore unstable. It will eliminate its extra energy as an electromagnetic pulse known as a gamma ray.
Gamma rays are like X-rays in that they penetrate matter, but they are more energetic than X-rays. Gamma rays are made of energy, not moving particles like alpha and beta particles. While on the subject of various rays, there are also cosmic rays bombarding the Earth at all times.
Cosmic rays originate from the sun and also from things like exploding stars. The majority of cosmic rays perhaps 85 percent are protons traveling near the speed of light , while perhaps 12 percent are alpha particles traveling very quickly.
It is the speed of the particles, by the way, that gives them their ability to penetrate matter. Please click here to see any active alerts. Estimate your yearly dose from the most common sources of ionizing radiation with this interactive online dose calculator. Radiation is energy. It can come from unstable atoms that undergo radioactive decay , or it can be produced by machines.
Radiation travels from its source in the form of energy waves or energized particles. There are different forms of radiation and they have different properties and effects. Non-ionizing radiation has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons from atoms.
Examples of this kind of radiation are radio waves, visible light and microwaves. Ionizing radiation has so much energy it can knock electrons out of atoms, a process known as ionization. Ionizing radiation can affect the atoms in living things, so it poses a health risk by damaging tissue and DNA in genes. Ionizing radiation comes from x-ray machines, cosmic particles from outer space and radioactive elements.
Radioactive elements emit ionizing radiation as their atoms undergo radioactive decay. Radioactive decay is the emission of energy in the form of ionizing radiation ionizing radiation Radiation with so much energy it can knock electrons out of atoms. The ionizing radiation that is emitted can include alpha particles alpha particles A form of particulate ionizing radiation made up of two neutrons and two protons. Alpha particles pose no direct or external radiation threat; however, they can pose a serious health threat if ingested or inhaled.
Some beta particles are capable of penetrating the skin and causing damage such as skin burns. Beta-emitters are most hazardous when they are inhaled or swallowed. Gamma rays can pass completely through the human body; as they pass through, they can cause damage to tissue and DNA.
Radioactive decay occurs in unstable atoms called radionuclides. The energy of the radiation shown on the spectrum below increases from left to right as the frequency rises. Other agencies regulate the non-ionizing radiation that is emitted by electrical devices such as radio transmitters or cell phones See: Radiation Resources Outside of EPA.
Alpha particles come from the decay of the heaviest radioactive elements, such as uranium , radium and polonium.
0コメント