| Date | November 2017 | Marks available | 2 | Reference code | 17N.3.HL.TZ0.16 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Estimate | Question number | 16 | Adapted from | N/A |
Question
An X-ray beam of intensity I0 is incident on lead. After travelling a distance x through the lead the intensity of the beam is reduced to I.
The graph shows the variation of ln\(\left( {\frac{I}{{{I_0}}}} \right)\) with x.
Show that the attenuation coefficient of lead is 60 cm–1.
[2]
a.
A technician operates an X-ray machine that takes 100 images each day. Estimate the width of the lead screen that is required so that the total exposure of the technician in 250 working days is equal to the exposure that the technician would receive from one X-ray exposure without the lead screen.
[2]
b.
Markscheme
evidence of finding the gradient
μ = «– gradient =» 59.9 «cm–1»
a.
I = \(\frac{{{I_0}}}{{25000}}\)
«ln 25000 = μx» x = 0.17 «cm» or 1.7 «mm»
b.
Examiners report
[N/A]
a.
[N/A]
b.
Syllabus sections
Option C: Imaging » Option C: Imaging (Additional higher level option topics) » C.4 – Medical imaging (HL only)
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