Question

A sheet of lead reduces the intensity of a beam of gamma-rays by a factor 0.4. Find the half value thickness of the lead sheet which will reduce the intensity to half of its initial value.

Answer 1

Let the intensity of the beam of gamma rays=Io
hence I=Io*e^(-n*x)).....where n is refractive index of the lead. and x is the thickness of it.
=>I/Io=e^(-n*x)
=>0.4=e^()

Answer 2

=>0.4=e^(-n*x)..(i)
similarly 0.5=e^(-n*x)...(ii)
from (i) and (ii) find x.
and the half value of thickness=x/2 .find it...