The Ultimate Guide

written by Stanley Udegbunam || Dec 22, 2020

radiation meaning



Radiation is the transport of thermally generated electromagnetic waves.

This mode of heat transfer does not require the existence of an intervening material medium for heat to be transferred from one surface to the other.

Rather, it can be transferred through a vacuum or through a medium that is either transparent or translucent to the radiation.

Radioactive atoms are atoms with unstable nuclei. To attain stability, these atoms emit the excess energy by radioactive decay. These emissions are called radiation.

Contrary to popular opinion, non-radioactive substances also emit radiation because radiation encompasses all forms of energy, not just those produced by radioactive decay.

However, all radioactive materials do emit radiation.


There are two types of radiation:

  1. ionizing and
  2. non-ionizing radiation.

The word “ionize” refers to the breaking of one or more electrons away from an atom.

Ionizing radiation is radiation traveling as a particle or electromagnetic wave, that carries sufficient energy to knock off electrons from atoms or molecules.

Radioactive elements emit ionizing radiation as their atoms undergo radioactive decay.

Ionizing radiation comes from radioactive elements, cosmic particles from outer space and x-ray machines.

Typical ionizing subatomic particles found in radioactive decay include alpha particles, beta particles and neutrons.

Ionizing radiation is used in a wide variety of fields such as medicine, nuclear power, research, construction and many other areas.

Exposure to such radiation can cause damage to living tissue, cancer and in intense cases, death.


Non-ionizing radiation has enough energy to move atoms in a molecule around or cause vibration, but not sufficient enough to remove electrons from atoms.

Examples of non-ionizing radiation are radio waves, visible light and microwaves.


  • Alpha Particle
  • Beta Particle
  • Gamma Ray
  • X – Rays

  • Alpha Particle 

They are positively charged and made of two protons and two neutrons from the atom’s nucleus.

Alpha particles are identical to the nucleus of a normal helium atom.

They are very energetic but only travel short distances.

Alpha particles can be very harmful, but they can’t penetrate the outer layer of the human skin.

They can be stopped by a sheet of paper.

  • Beta Particles

They are small, fast-moving particles with a negative electrical charge that are emitted from an atom’s nucleus during the radioactive decay of an atomic nucleus.

A beta particle has the same mass and charges as an electron.

Beta particles travel farther in air than alpha particles.

They are also more penetrating but can be stopped by a thin aluminum plate.

  • Gamma Rays

Also called photons, they are similar to visible light but have much higher energy.

Gamma rays consist of the shortest wavelength electromagnetic waves and so imparts the highest photon energy.

They can penetrate the human skin, therefore they are highly hazardous.

Gamma rays require shielding by dense material such as lead, or concrete.

  • X – Rays

X-rays wavelengths are shorter than those of U.V rays and typically longer than those of gamma rays.

X-rays and gamma rays have the same basic properties but come from different parts of the atom.

They are generally lower in energy and therefore less penetrating than gamma rays. 

X-rays are utilized mostly in the medical field to view images of the bones and other structures in the body.




Electromagnetic Spectrum is the distribution of all electromagnetic waves arranged according to their frequency and wavelength.

The energy of the radiation shown on the spectrum below increases from left to right as the frequency rises.


The international symbol used to indicate radioactive sources, radioactive materials and radioactive storage area is known as the trefoil.

The trefoil is a black propeller on a yellow background.

radioactive symbol

radiation caution

The presence of this symbol denotes the need for caution, a warning to avoid contamination with or undue exposure to atomic radiation.

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