Alpha, Beta and Gamma Radiation

0:00At the centre of an atom is a tiny nucleus. Here it is, packed with protons and neutrons.

0:08Some nuclei are unstable. To become more stable, they give off radiation, as fast particles or as waves of energy.

0:17There are three common kinds of radiation: alpha, beta and gamma.

0:23Which of them can get through paper, aluminum and lead?

0:28Alpha radiation is a particle of 2 protons and 2 neutrons, so its charge is plus 2.

0:35A single sheet of paper stops alpha.

0:39In some nuclei, a neutron changes into a proton, and a fast electron shoots out.

0:46This fast electron is beta radiation, with a charge of minus 1.

0:51Beta passes through paper, but a few millimetres of aluminum stop it.

0:56Gamma radiation is a high-energy electromagnetic wave, like light but with far more energy.

1:04Unlike alpha and beta, it has no charge.

1:08Gamma passes through paper and aluminum. Several centimetres of lead reduce it, but some still gets through.

1:16Outside the body, skin stops alpha, but that does not make it harmless.

1:21If a substance that gives off alpha is swallowed or breathed in, it is inside the body, next to living cells, and can badly damage them.

1:31Paper stops alpha, aluminum stops beta, and thick lead reduces gamma.