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CC 2015-2016 QCM 14


Go to solution Solved by Chat_du_Cheshire,

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Posted

Bonjour, je n'arrive pas à répondre aux items C, D et E de ce QCM.. 

Quelqu'un voudrait bien m'aider svp ?1804968598_Capturedcran2019-01-1710_52_54.png.6951ba6257cc9fb06b34f62b625f68ab.png

  • Solution
Posted

Heyyy

 

Alors la CDA vaut ln(2)/coef d'atténuation linéique total = 0.7/0.5 = 1.4

 

Donc au bout de 1.4 cm. 50% du flux de photons est attenué (N/2^1).

Au bout de 2.8 cm, il y a donc 2 CDA soit 2^2 = 4 au dénominateur, on a donc N/4, donc 75% a été atténué donc C FAUX

 

7 cm = 5*1.4 = 5 CDA, soit 2^5 = 32 donc atténuation d'un facteur 32, D VRAI et E FAUX

 

voilou

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