Types of Radiation

1. The term "radiation" is often used to refer to different things. There are two main types of radiation: electromagnetic waves and high energy particles. When people use the term "radiation" sometimes they are refering to electromagnetic wave, sometimes high energy particles, and sometimes both.
2. Electromagnetic Radiation
   1. Electromagnetic Radiation is a type of energy that travels in waves.
   2. Types of EMR
      1. Radio waves
      2. Microwaves
      3. Infrared
      4. Visible light
      5. Ultra Violet
      6. X-Rays
      7. Gamma Rays
      8. Handout: Electromagnetic Waves
   3. To talk of a particular kind of energy we can discuss the energy, wavelength, or frequency of the wave.
      1. Wavelength is the distance from the peak of one wave to the peak of another.
      2. Frequency is the the number of waves per second that a stationary observer would count while the wave is passing by.
      3. Energy, frequency, and wavelength are all interrelated due to the fact that all EMR travels at the same speed. As wavelength decreases, frequency increases, and energy increases
      4. Gamma rays have the highest frequency, shortest wavelength, and highest energy. These are represented by the following symbol:
      5. Lower energy forms of EMR (radio, infrared, etc.) are not harmful.
3. High Energy Particles
   1. Tiny subatomic particles can have high energy if they are moving at very fast speeds.
   2. The most common forms of high energy particles are:
      1. Alpha Particles
         1. These are represented by the following symbols: or
         2. As you can see from the symbol above an alpha particle is the same as the nucleus of a Helium atom (or a Helium atom with no electrons), a cluster of two protons and two neutrons.
      2. Beta Particles:
         1. These are represented by the following symbols: or
         2. As you can see from the symbol above a beta particle is the same as an electron.
      3. Neutrons:
         1. These are represented by the symbols: n or
   3. All of the particles above get their high energy when they are ejected from the nucleus of an unstable atom. That is why they are all the familiar particles - protons, neutrons, and electrons - that make up atoms.
4. Radioactivity
   1. Radioactive substances emit some or all of the particles above, as well as, gamma rays, the highest energy form of the electromagnetic waves. Other forms of electromagnetic radiation (x-rays, light, radio, etc.) are not directly emitted by radioactive substances.
   2. Some radioactive substances emit primarily alpha, beta, or gamma. Most emit several types of radiation as the nucleus decays and becomes more stable.
   3. When and how this radiation is released will be discussed later.