For most of the sources you encounter in on a regular basis life, the quantity of radiation is so low that you simply don’t want to fret about it. But ionizing radiation can be harmful, as a result of these free electrons work together with the molecules within the cells and tissues of the human physique. Adding an additional electron can break the chemical bonds that maintain molecules collectively. That is why the radioactive substances related to nuclear weapons and power plant meltdowns can increase the risk of cancer.

There are 4 varieties of ionizing radiation: alpha, beta, gamma, and neutron radiation. Here’s what is going on on with every sort and the way they are often detected.

Alpha Particles

In 1896, nobody actually knew something about radiation. They did not know if it was a particle or some sort of electromagnetic wave, like mild. So they determined to make use of the time period “rays” within the generic sense—like mild rays. That’s how we get holdover phrases like alpha rays or gamma rays.

But—SPOILER ALERT—alpha rays will not be waves. They are literally electrically charged particles. An alpha particle is product of two protons and two neutrons. This signifies that an alpha particle is a helium atom with out the electrons. (Yes, they need to have referred to as them “helium particles,” however nobody knew what was occurring.)

How are you able to inform that it’s alpha radiation, and never another sort? The reply is that alpha particles can simply be blocked by one thing as skinny as a sheet of paper. So you probably have a supply that produces alpha particles, you possibly can defend the detector—like photographic movie—with a really small quantity of fabric.

The purpose that alpha particles are so simply blocked is that, as a result of they’re so heavy, they’re usually ejected from the radioactive supply with a comparatively sluggish velocity. Also, with {an electrical} cost equal to 2 protons, there’s a important electrostatic power between the alpha particle and the optimistic nucleus of the shielding paper. (We name this a cost of twoe, the place e is the elemental cost of an electron or proton.) It does not take too many of those atoms within the paper to primarily deliver the alpha particle to a cease.

Do what else can cease an alpha particle? Human pores and skin. That’s why alpha radiation is commonly thought-about to be the least dangerous of the radiation sorts.

Beta Particles

In 1899, Ernest Rutherford labeled three varieties of radiation: alpha, beta, and gamma. While the alpha particles had been simply stopped, beta and gamma particles might undergo some quantity of metallic shielding, penetrating additional into materials as a result of they’re much decrease mass. In truth, beta particles are electrons—the elemental particles with a detrimental cost. The mass of an alpha particle is greater than 7,000 occasions bigger than that of a beta particle. This signifies that very low-mass beta particles might be emitted with very excessive speeds that give them the flexibility to penetrate objects, together with the human physique.

Gamma Rays

Gamma rays are truly rays, not particles. They are the third class of radiation, and a sort of electromagnetic wave—identical to seen mild.

However, the sunshine that you may see together with your eyes has a wavelength between 400 and 700 nanometers, whereas gamma rays have a a lot smaller wavelength. A typical gamma ray might need a wavelength of 100 picometers. (Note: 1 picometer = 10^-12 meter, and 1 nanometer = 10^-9 meter.) This signifies that the wavelength of gamma radiation might be round 1,000 occasions smaller than seen mild. With such a small wavelength, and a really excessive frequency, gamma rays can work together with matter at very excessive power ranges. They may penetrate fairly deep into most supplies, so it often takes a big chunk of result in block this radiation.