Half-Life (OCR GCSE Physics A (Gateway Science Suite)): Flashcards

Time for half nuclei to decay or activity to halve

Constant

$5$ min ($2$ half-lives)

Very radioactive initially, quickly dies down

Weakly radioactive for long period

$432$ years

Smoke alarms (alpha emitter)

Long half-life: won't need replacing; weak activity: not harmful

Number of radiation counts per second

Rate of decay ($1$ Bq = $1$ decay/second)

Never reaches zero

$160$ Bq ($25$% of initial)