11th Sep '25

Properties of Radiation

When radiation from radioactive materials collides with neutral atoms or molecules these may become charged (ionised). When radiation ionises molecules in living cells it can cause damage, including cancer.

The larger the dose of radiation the greater the risk of cancer. As radiation passes through a material it can be absorbed. The greater the thickness of a material the greater the absorption:

alpha (α) radiation, easily absorbed by of air or a thin sheet of paper;
beta (β) radiation, easily passes through air or paper but is mostly absorbed by of metal;
gamma (γ) radiation, is very penetrating and requires of lead or metres of concrete to absorb most of it.

When sources of radiation are outside the body:

beta and gamma radiation are the most dangerous because they can reach the cells of organs and may be absorbed by them;
alpha radiation is least dangerous because it is unlikely to reach living cells.

Workers who are at risk from radiation often wear a radiation badge to monitor the amount of radiation they have been exposed to over a period of time. The badge is a small packet containing photographic film. The more radiation a worker has been exposed to, the darker the film is when it has been developed.

When sources of radiation are inside the body:

radiation is the most dangerous because it is so most ionising and is strongly absorbed by the cells;
beta and gamma radiation are less dangerous because cells are less likely to the radiation.

and beta radiations are deflected by both and fields but radiation is not.

particles are deflected less than beta particles and in directions. This is due to alpha having a greater mass and a charge while beta is charged.

Summary 'Cut and Stick'
Worksheet