Pocket Genius Science: Energy and forces – Radioactivity

Facts At Your Fingertips: Energy and forces – Radioactivity

In some atoms, the nucleus changes over time, releasing particles and energy, known as radiation.

This process is called radioactive decay. We encounter low-level radiation all the time—in the soil, in the air, and in the food we eat.

Types of radioactivity

There are three types of radioactivity: positively charged alpha particles, which are slow-moving and cannot pass through materials easily; negatively charged beta particles, which move much faster; and gamma rays—a form of electromagnetic radiation (see pages 68–69)—which carry no charge.

Detecting radiation

Radiation is invisible, but it can be detected using a Geiger counter.

This simple handheld device uses a gas-filled tube to measure the presence of alpha particles, beta particles, and gamma rays.

Using radiation

While high levels of radiation can be harmful, some forms of radioactivity are useful.

PET scanners use gamma rays to produce highly detailed images of the inside of the body, which can help doctors to diagnose illnesses.