radioactivity
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radioactivity
The property of unstable atomic nuclei to transform spontaneously while releasing energy. In this process, ionizing radiation, such as alpha, beta, or gamma radiation, is emitted.
Nach dem Reaktorunfall wurde in der Umgebung eine erhöhte Radioaktivität gemessen.
After the reactor accident, increased radioactivity was measured in the surrounding area.
The word is made up of 'Radio-' (from Latin radius, 'ray') and 'Aktivität' (activity). So it literally describes a kind of 'radiation activity'. The ending '-ität' forms an abstract noun from the adjective 'radioaktiv' (radioactive).
Die Radioaktivität des Materials war unerwartet hoch.
The radioactivity of the material was unexpectedly high.
'Radioaktivität' (radioactivity) is an uncountable noun (singulare tantum). It is used like a mass noun, such as water or air, and therefore usually has no plural.
Man kann Radioaktivität nicht sehen oder riechen.
You cannot see or smell radioactivity.
This word is a technical term from physics and is used mainly in scientific, technical, or safety-related contexts.
Der Experte erklärte die Gefahren durch Radioaktivität.
The expert explained the dangers caused by radioactivity.
Common combinations are 'Radioaktivität messen' (to measure radioactivity), 'Radioaktivität freisetzen' (to release radioactivity), or 'sich vor Radioaktivität schützen' (to protect oneself from radioactivity). It is often combined with adjectives such as 'hoch' (high), 'gering' (low), or 'erhöht' (increased).
Die Messgeräte zeigten eine leicht erhöhte Radioaktivität an.
The measuring devices indicated slightly increased radioactivity.
radiation
'Strahlung' and 'Radioaktivität' are closely connected because radiation can be produced by radioactivity. But the difference is important: 'Strahlung' means the energy itself, which spreads as waves or particles, for example light, heat, or radioactive radiation. 'Radioaktivität' means the property of certain atomic nuclei to change and emit radiation in the process. Learners may confuse the words because people often talk about danger, measurement, and protection. In practical terms, you can say: radioactivity is the cause or property; radiation is what is emitted as a result.
Im Kurs erklärt die Lehrerin heute, warum Radioaktivität für den Körper gefährlich sein kann.
In class today, the teacher explains why radioactivity can be dangerous for the body.
Bei starkem Sonnenlicht schützt die Creme die Haut vor gefährlicher Strahlung.
In strong sunlight, the cream protects the skin from dangerous radiation.