Question

What fraction of 5 MeV α particles will be scattered through angles greater than 12° from a gold foil (Z = 79, density = 19.3 g/cm³) of thickness 10^-8 m?

Answer 1

Fraction of incident particle scattered by an angle and greater is given as:

Where,

t = thickness = ​​​​​​

Z₁e = charge of alpha particle = 2e

Z₂e= charge of gold foil = 79e

K = kinetic energy of alpha particle ​​​​​​

n = density of target particles

Which is given as:

Where,

Density

(i.e 1 in this case)

Gram molecular weight =

By putting values n will be :

Now,

By putting the values value of fraction is: