Physics: At the Heart of Everything

There are three main classification of radiation: 

• Alpha radiation (α)
  
• Beta radiation (β)
• Gamma radiation (γ)

Each of these types of radiation are ionizing radiations. This means that they have the ability to remove electrons from atoms so that the atoms become ions. 

• Alpha particles consist of two protons and two neutrons moving at high speeds. They can also be refereed to as helium nuclei because one particular isotope of helium (helium 4) contains two protons and two neutrons in its nucleus. Alpha particles are easily stopped by a physical barrier. As shown above, they cannot even penetrate the paper. 
• Beta particles are highly energetic electrons or positrons moving at high velocities. For those that do not know, positrons are the antimatter equivalent of the electron. Beta radiation can more easily go through substances but it can be blocked by a thin sheet of aluminium. 
• Gamma radiation consists of the highest frequency band of electromagnetic radiation. Gamma rays are so energetic that it takes a block of lead a few inches in thickness to completely block it out. 

As I already mentioned, all of these types of radiation are ionizing. This makes them potentially harmful to humans and to other life forms. When atoms in our body become ionized through interactions with radiation, this can lead to damage to our cells and to our DNA. 

There are other types of electromagnetic radiation that are classified as non-ionizing. These are the lower frequencies of the electromagnetic spectrum.  

The above image illustrates the different types of electromagnetic radiation. Gamma rays are at the highest energy end, then comes x-rays and ultra-violet radiation. X-rays and certain frequencies of ultra-violet rays are ionizing. When you travel down the rest of the spectrum, the frequency, and therefore the energy of the radiation decreases. This means that they no longer have the ability to ionize atoms. Non-ionizing radiation includes:

• Visible light 
• Infrared radiation (heat)
• Microwaves and Radio waves (used in microwave ovens, telecommunications, WiFi, Bluetooth etc)

Although they are non-ionising, they still have the potential to damage us by heating effects. For example ultra-violet radiation that is classified as non-ionizing causes sun-burn. However this risk is minimal compared to the effects of ionizing radiation. There is little evidence that mobile phone usage, WiFi or radio masts (often called phone masts) have adverse health effects. 

(Image credit 1, 2 )