Exam-style question
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How does the intensity of an X-ray beam change with distance from the source?.
- A.It increases linearly with distance.
- B.It decreases with the square of the distance.
- C.It remains constant regardless of distance.
- D.It decreases exponentially with distance.
Model answer
What a good answer should say
- It decreases with the square of the distance.
Explanation
Why this works
The intensity of an X-ray beam follows the inverse square law, meaning that as the distance from the source increases, the intensity decreases proportionally to the square of the distance. This is due to the spreading of the beam over a larger area.
Common mistake
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