Exam-style question
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If a material has a half-value thickness of 3 cm, what thickness would be needed to reduce the intensity of X-rays to 12.5%?.
- A.6 cm
- B.9 cm
- C.12 cm
- D.15 cm
Model answer
What a good answer should say
- 9 cm
Explanation
Why this works
To reduce the intensity to 12.5%, the material must be passed through 3 half-value thicknesses (3 cm each). Therefore, the total thickness required is 3 cm x 3 = 9 cm.
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