Question detail
What happens to the current in an ionisation smoke alarm when smoke enters?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Hazards and uses of radioactive emissions and of background radiation
Question
- A. The current increases
- B. The current decreases
- C. The current remains the same
- D. The current fluctuates
Answer
The correct answer is B: The current decreases.
Explanation
The correct answer is B: The current decreases. This supports the learning objective "Explain how smoke entering an ionisation smoke alarm changes the current and triggers an alarm." in Uses of nuclear radiation because it uses the correct atomic and nuclear radiation relationship for Hazards and uses of radioactive emissions and of background radiation. The other options are less suitable because they do not match the required Uses of nuclear radiation idea: The current increases; The current remains the same; The current fluctuates.
Common mistake
Misunderstanding Smoke Alarm Function
Students often think that smoke alarms only detect smoke particles without understanding the role of ionisation.
Explain that smoke entering the ionisation chamber disrupts the ionisation process, reducing current flow and triggering the alarm.
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