Learn about the reality and pervasiveness of radiation in our world. Discover some of the causes of radiation, and find out about the risks and rewards of harnessing it for our use.

The Nature of Radiation

Radiation may bring to mind the superheroes and monsters of comic books and movies, but radiation is very real and all around us! In fact, you are currently being bombarded by radiation. It might be coming from the sun, various electronic devices you own, or even the food in your kitchen. If you have ever eaten a banana, you have eaten a radioactive material. The good news is that the vast majority of radiation you are exposed to is relatively harmless.

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Whether or not radiation can harm you depends on the type of radiation, the dosage you come in contact with, and the length of the exposure. Here we’ll go over the different types of radiation, their causes, uses to us, and dangers. Before we get started, you need to know what exactly radiation is in general. Radiation can be defined as the transmission of energy from a body in the form of waves or particles. This can encompass anything from dangerous radiation created by a nuclear power plant to the harmless light created by a flashlight.

Ionizing and Non-Ionizing Radiation

Before we go any further, let’s cover some basic terms. Ionization is the process in which an atom either loses or gains an electron. Since electrons are negatively charged, this process will take an atom, which normally has no charge, and give it either a positive or negative charge depending on whether it lost or gained electrons. An atom that has a charge to it is called an ion.

So the difference between ionizing radiation and non-ionizing radiation is that ionizing radiation has enough energy to strip electrons off of atoms, and non-ionizing radiation does not have enough energy to strip electrons off of atoms. One of the easiest ways to visualize the difference between these two is to look at the frequency spectrum for light. As the frequency goes up, so does energy, so we can see the energy cut off for light where it goes from non-ionizing to ionizing radiation is within the ultraviolet light spectrum. Now let’s look at the causes of both types of radiation.

Causes of Radiation

Non-ionizing radiation is limited to the lower energy range electromagnetic radiation, which is more commonly known as light. However, the light we can see with our eyes, visible light, is only a small section of the electromagnetic radiation spectrum as seen here.

Electromagnetic radiation spectrum
frequency spectrum of electromagnetic radiation

All types of light are a type of radiation. The most common way this type of radiation is created in our universe is by stars like our sun. Inside stars, hydrogen atoms are constantly bouncing around, and under great pressure and temperature. Two hydrogen atoms can collide and form a helium atom. This is a process known as nuclear fusion. In this fusion process, energy is given off as a byproduct. This energy is the electromagnetic radiation created by the stars.

On a smaller scale, a light bulb is a good second example of how non-ionizing radiation can be created. In a light bulb, electricity is passed through a tungsten filament surrounded by an inert gas that keeps the filament from catching fire. The electrons put into the filament constantly collide with the tungsten atoms, causing them to vibrate. This atomic vibration then gives off radiation in the form of heat and light. Vibrating atoms are another common cause of non-ionizing radiation.

Given that ionizing radiation is high-energy radiation and non-ionizing radiation is low-energy radiation, it might have seemed strange to you that nuclear fusion is a process that creates low-energy radiation. In fact, nuclear fusion in stars is a special case. It creates both high and low energy radiation.

The types of ionizing radiation most commonly talked about are those created by radioactive decay. This is when unstable atoms try to rearrange themselves in some way to change their energy and become stable. The three most common types of this kind of radiation are alpha decay, beta decay, and gamma decay.

In alpha decay, the atom changes its energy by spitting out two neutrons and two protons, which happens to be the nucleus of a helium atom. In beta decay, the atom spits out either an electron or a positron, which is the antimatter counterpart to an electron. In gamma decay, unlike the other two, the atom does not actually remove a piece of itself. Instead, the atom tries to change its energy by rearranging the neutrons and protons in its nucleus. As a side effect of this, it releases an extremely high energy photon called a gamma wave.

Much like the flashlight in non-ionizing radiation, ionizing radiation can also be created artificially. One example would be nuclear fission in a power plant. Where nuclear fusion combined two atoms together, nuclear fission breaks one apart. By bombarding a specifically prepared uranium rod with neutrons, a nuclear reactor is capable of breaking the uranium atom apart. This process releases a large amount of energy in the form of radiation. The energy can then be harnessed to create electrical power.

Uses for Radiation

So what are some uses for radiation?

Non-ionizing radiation is the kind that’s all around us in the various electronic devices we use. Microwaves are used in the aptly named microwave for cooking meals. Radio waves transmit voices across the world into and out of our car radios. The radiation used for cell phones falls somewhere in between the radio and microwave spectrum and is used in a similar fashion to radio waves. You might at some point have seen on television a police chase where a helicopter uses an infrared radiation in a camera to see heat sources and spot a suspect in the dark. But, did you know your television remote is using that same infrared to communicate with the TV when you press buttons on it? Finally, we even use low energy ultraviolet radiation in tanning beds.

Ionizing radiation is far less commonly used, but it still has its place. One such use is for carbon dating. In every living thing, there are carbon-14 atoms, an unstable atom that experiences beta decay. While we live, the supply of this atom is replenished in our bodies, but when someone dies, the supply stops. Knowing how fast carbon-14 decays, archaeologists can check how much remains in a person, animal, or plant to get an estimate on how old it is.

Another area where ionizing radiation is commonly used is the medical field. X-rays are another form of ionizing radiation created through the same process as gamma rays, but they have less energy. X-rays are commonly used to look at your skeleton in everything from searching your teeth for cavities to seeing how badly someone’s bones are broken after a serious injury. Another common use is in radiation therapy for those suffering from cancer. We use radiation on cancer cells for directly damaging the DNA inside them to kill the cancer and stop it from spreading.

Dangers of Radiation

While radiation can be helpful to us, it can also be dangerous. This danger is dependent on the type of radiation, dosage you took in, and the amount of time you were exposed. In general, the dangers of non-ionizing radiation are less severe than ionizing radiation. Most common among the health effects caused by extreme exposure to low energy electromagnetic radiation are burns to the skin caused by microwave, infrared, visible, and ultraviolet radiation. If you’ve ever gotten a sunburn from spending too much time out at the beach, then you have firsthand experience with this effect of radiation. Overexposure to ultraviolet light has been linked to skin cancer. It’s no coincidence that the type of electromagnetic radiation that blurs the line between non-ionizing and ionizing radiation has the most severe health effect associated with it.

Alpha decay cannot even penetrate human skin. Exposure to alpha decay radiation can only hurt you if it somehow gets inside your body through an orifice or open wound. Radiation from beta decay is capable of partially penetrating the skin, but it cannot get all the way through it. Because of this, skin damage is the most common side effect of overexposure to beta decay radiation. Finally, gamma decay and x-ray radiation, the most dangerous, are able to penetrate all the way through the skin into your body. With gamma decay and x-ray radiation, even our uses for it can be dangerous to us. Health effects of radiation can include vomiting, diarrhea, hair loss, hemorrhaging, intestinal damage, internal bleeding, central nervous system damage, growth defects in unborn children, and even death.

Lesson Summary

Radiation can be defined as the transition of energy from one body in the form of waves or particles. Radiation can be split into the two main categories of non-ionizing and ionizing radiation. Ionization is the process in which an atom loses or gains an electron to become positively or negatively charged. Non-ionizing radiation encompasses the electromagnetic spectrum from low energy ultraviolet light on down through the lower frequencies. Two ways non-ionizing radiation can be caused is nuclear fusion in a star and by atomic vibrations giving off energy. Ionizing radiation includes the higher frequencies of the electromagnetic spectrum from high energy ultraviolet light on up, radioactive decay from unstable atoms, and nuclear fission. Radiation can be harnessed to work in many modern devices, assist archaeologists in carbon dating, and for medical uses. However, radiation can also be very dangerous. It is capable of causing everything from sunburns to death depending on the type, amount, and length of radiation exposure.

Radiation: Key Terms

Myths of Radiation Effects
radiationmyths
  • Radiation: transmission of energy from a body in the form of particles or waves
  • Ionization: a process where an atom loses or gains an electron and becomes positively or negatively charged
  • Non-ionizing Radiation: includes the electromagnetic spectrum from low energy ultra-violet light down through lower frequencies
  • Ionizing Radiation: represents the higher frequencies of the electromagnetic spectrum from high energy ultraviolet light on up
  • Alpha Decay: an atom changes its energy by producing two protons and two neutrons
  • Beta Decay: an atom spits out either an electron or a positron
  • Gamma Decay: an atom changes its energy through rearranging neutrons and protons in the nucleus

Learning Outcomes

After students finish this lesson, they should be able to:

  • Define radiation
  • Distinguish between ionizing radiation and non-ionizing radiation
  • Discuss the causes of radiation
  • Identify safe uses of radiation
  • Explain the dangers associated with radiation