Properties of Electromagnetic Radiation

 

 The follow lists the properties that all EM radiation possess. 

Since EM radiation shares many of the same properties due to laws of physics, and we can see visible light, we will be able to demonstrate many x-ray properties using a flashlight. More on that later...

 


Properties of X-rays

What is the difference between X-rays and Gamma rays?

As you've seen from the electromagnetic spectrum, x-rays and gamma rays occupy the upper end (higher energy) of the spectrum.  They can actually have the same energy and do share the same part of the spectrum.  The difference between the two is in its origin, meaning how they are created.  Both are created through interactions with atoms.  X-rays occur during interactions within the electron cloud of an atom.  Gamma rays occur within the nucleus of an atom during radioactive decay.  There is more energy to be had in the nucleus of an atom, so gamma rays do have the capacity to be much higher in energy. 

To summarize - X-rays and gamma rays are both forms of electromagnetic radiation and both are ionizing radiation. 

Gamma Rays - Originate in the nucleus of an atom.  It is a product of radioactive decay of radioactive elements.

X-rays - Originate in the electron cloud of an atom.  It can be a byproduct of radioactive decay, which you'll be happy to know we won't go into, or created electronically with x-ray machines, which we most definitely will expand on.

There are also other forms of ionizing radiation that you should be aware of.  They are not electromagnetic, meaning they are not photons like x-ray and gamma rays.  They are elementary subatomic particles (protons, neutrons, electrons).

Alpha Particles - Alpha particles consist of 2 protons and 2 neutrons.  It is the result of radioactive decay. They can not travel very far, perhaps just a couple of centimeters.  They do not penetrate objects as x-rays do.  A mere piece of tissue paper can stop them.  A common source of alpha radiation is radon.

Beta Particles - Beta particles are high speed electrons.  They can be created during radioactive decay of elements.  The high speed electrons created within a x-ray tube can be considered beta particles.  They can travel farther than alpha particles and they do have the ability to penetrate objects, such as the body.  As they penetrate the body, they interact with matter and transfer energy.  The more energy the beta particle has, the deeper it can penetrate before being completely absorbed.  This makes it a very useful tool in medicine.  Knowing the energy and controlling the penetration ability allows us to use it in radiation therapy, where the goal is to irradiate a specific area at a specific depth.

Alpha particles generally have more energy than beta particles, which in turn have more energy than x-rays.  Why is that?  The simple answer is mass.  X-rays are pure energy with no mass.  Beta particles are electrons, so have mass.  Alpha particles are made of 2 protons and 2 neutrons, which has a LOT more mass.  Think of the energy of a moving train (alpha), compared to a moving bicycle (beta), compared to tossed grape (x-ray). Which of these would cause the most damage when it reacts with a wall?