This key facts covers Finding Half-Life from Data within Half-Life for GCSE Physics. Revise Half-Life in Atomic Structure for GCSE Physics with 15 exam-style questions and 23 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 4 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📚 Finding Half-Life from Data
Method 1: From a table
- Find the time when activity halves (e.g., 1000 → 500)
- That time interval = one half-life
- Check by seeing if it halves again in the same time
Method 2: From a graph
- Read the starting activity from y-axis
- Find half of this value
- Draw a horizontal line at half-value
- Where it meets the curve, draw vertical line to x-axis
- Read off the time = half-life
Quick Check: A graph shows activity dropping from 600 Bq to 150 Bq over 20 minutes. What is the half-life?
600 → 300 → 150: this is 2 half-lives. 2 half-lives = 20 minutes, so one half-life = 10 minutes.
Practice questions for Half-Life
What is the definition of half-life?
Explain what is meant by saying radioactive decay is 'random and spontaneous'.