Finding foil thickness for equal X-ray absorption with different materials

[jagguy]

Homework Statement

This i self study!
Hi, How thick should a foil made from absorber II be to give the same absoption as 1mm thick foil made from absorber I for xrays with energy 5X10⁶


xray beam passing through an absorption material it is attenuated , this is given by

I/I_o e^-ax

i_o =initial intensity of the beam
i=intensity of beam from absorber taken as average amount of photons emerging from 1cm²
x=thickness of slab of absorbing material in cm^-1
a=linear attenuation material
e=2.718

table photon energies 5X10⁶
absorber 1 .4
absorber 2 .2

Homework Equations

linear attenuation coefficient=% reduced/thickness of absorber

The Attempt at a Solution

used logs to find x

tried to use linear attenuation coefficient
but really got stuck on what to do

 

[jagguy]

I/Io= e-ax

 

[jagguy]

I/Io =e^-ax

 

[jagguy]

i go t an answer of 2mm because ax value where a is halved so x is doubled to keep same formula