So radiation is definitely a term that is thrown around a lot by many people. For the general population, there definitely seems to be some negativity associated with the term. Let’s have a look at radiation that is on the spectrum and properly assess the pros and cons of its existence in this world. Regardless of us being here or not, it would exist.
So radiation is the movement of energy in the forms of particles or waves and it is broken up into a variety of different types depending on its energy level and wavelength (high energy equals short wavelength and vice versa). Depending on the type of radiation determines the medium that it can travel through; whether it travels through material (solid, liquid, gas) or through space. Before we get into the different types, we’re going to distinguish two main categories of radiation; ionizing and non-ionizing radiation. Ionizing radiation is radiation that is so strong (high energy) that it has the ability of knocking an electron off an atom making it an ion (charged atom either negative or positive). Types consist of gamma rays, X-rays, ultraviolet radiation (UV) as well as alpha and beta radiation that has to do with radiative decay (similarities to gamma radiation). Non-ionizing radiation on the hand doesn’t possess enough energy to change the charge of an atom (knock off an electron) when passing through matter. There are some subtypes of UV radiation that fit in this group as well as visible light, infrared (IR) radiation, microwaves and radiowaves.
Gamma Radiation (wavelength: < 3 x 10^-11 m)
This is a type of radiation that is in the form of a photon (light) and occurs in radioactive decay when an unstable atom releases excessive energy. Due to light not having any mass or charge, it takes thick layers of dense materials like lead to absorb a part of the radiation. Most of this radiation is absorbed by the atmosphere and redirected around Earth. It can not be stopped completely however with astronauts (minimal protection from the atmosphere) are affected by many forms of radiation when in space (cosmic radiation).
Beta radiation comes in two types; plus and minus. Beta minus is when an electron is emitted whereas beta plus is a positron (opposite of an electron). Sometimes used in radiation therapy of cancers close to the surface (superficial), this form of radiation can be stop by layers of metals (aluminum) or plastics and glass.
Alpha radiation is the largest form of radiation consisting of a helium-4 nucleus. Due to it’s size, it interacts with matter around it easily so can only pass through a couple of centimeters of air. Your clothing and even your skin is enough to stop this radiation; the only time it becomes dangerous is when it makes its way into the body (ingested or inhaled).
X-rays (wavelength: <10^-9m)
We’ve all heard of X-rays before and you’ve probably had one before. When an X-ray passes through material it can do one of 2 things; either energize the atom to a higher energy state or ionize the atom by knocking off an electron. Due to this difference in how different substances absorb the rays, it allows for doctors to see inside of you. Bone is made of larger atoms than soft tissue which is made of relatively smaller atoms so the amount of x-rays absorbed is different.
Ultraviolet (wavelength: 10 to 125 nanometers (nm))
There is different types of UV radiation but most is absorbed by the ozone layer around the Earth; except for UV-B and UV-C. These subtypes of UV radiation does make it to Earth and it is these that a dangerous to us on the surface. When it comes into contact with your skin, it can excite some molecules within resulting in reactions that can damage tissue and DNA. The purpose of sunscreen is to deflect these types of radiation to minimize your bodies exposure so remember to slip, slop, slap; even on overcast days.
Visible Light (wavelength: 380 to 750 nm)
The only stuff in this massive spectrum that we can see thanks to the evolution of our eyes. This is the type of radiation that starts to fall into the non-ionising radiation group and it continues on from here. Different surfaces absorb different wavelengths differently and reflect the wavelengths that it can’t absorb. So something that appears to be green is actually absorbing all other wavelengths except for the wavelength that reacts to green in our eyes. Red things reflect red light, blue things reflect blue light whereas black absorbs all light and white reflects all visible light.
Infrared (wavelength: 0.7 to 300 micrometers (μm)
IR radiation can be felt as heat light what you might feel holding your hand to a flame. It is this heat that has resulted in snakes developing biology called pits that allows them to feel for it which was then adopted by the military when completely night objectives; IR radiation allows for us to see in the dark with night vision goggles.
Microwaves (wavelength: 1mm to 1m)
This is used to reheat your food! The microwaves make molecules of water vibrate enough that they start to heat up. That’s why foods with a low water content (mash potato) will take longer to heat up then food like leafy vegetables and steak. This is also used for radar and some old school truck communication.
Radiowaves (1m to 1km)
Natural made by some large astronomical objects and lightning (why there is interference during a storm), we’ve utilized this radiation for almost all forms of communication such as phone, television and radio. There are still some radiation forms that have longer wavelengths than radio waves like very low and extreme low frequency with wavelengths up to 10,000+ km.
That’s it for the simple breakdown of radiation. There is some type of radiation passing through every centimeter of matter every second and though some of it is dangerous. Humans have utilized it to see, communicate, transverse the world and even reheat last night’s pizza. Specialised telescopes also allow us to look into the different types of radio waves as well as UV, IR and x-rays coming from space allowing for some pretty amazing images to be created. Radiation is simply amazing and the world would be unimaginably different without it. Like, we wouldn’t be here.