CAIE A-Level Physics 24.2.3 X-Ray Attenuation

Practise calculating X-ray transmission and absorbed energy through single materials or layers using exponential attenuation and percentage changes.

Exam points

use I = I₀e⁻μx to calculate X-ray transmission through matter
calculate absorbed energy or percentage from X-ray attenuation

[Maximum number: 2]

A parallel beam of X-ray radiation is incident, separately, on samples of bone and of muscle.

Data for the thickness x of the samples of bone and of muscle, together with the linear attenuation coefficients $\mu$ of the radiation in bone and in muscle, are given in Table 10.1.

Table 10.1

Calculate the ratio
> intensity of radiation transmitted through the bone
> intensity of radiation transmitted through the muscle ⋅

ratio =

$I=I_{0} \exp (-\mu x)$

C1

ratio $=(\exp \{-1.5 \times 2.9\}) /(\exp \{-4.0 \times 0.95\})(=\exp \{-0.55\})$

ratio = 0.58

A1

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24.2.3—I = I0e–µx for the attenuation of X-rays in matter question 1