# 3: Atomic models¶

## Example number 3.1, Page number 45¶

In [7]:
#importing modules
import math
from __future__ import division

#Variable declaration
rho=19.3;   #density(g/cc)
A=197;   #atomic weight(g)
k=8.984*10**9;  #value of k(Nm**2/C**2)
Z=79;
Zdash=2;
e=1.6*10**-19;   #conversion factor from J to eV
m=2;
v0=8*10**6;
t=2*10**-6;   #thickness(m)

#Calculation
n=N*rho*10**6/A;    #number of atoms(per m**3)
b=k*Z*Zdash*e/(m*v0);   #impact parameter(m)
f=math.pi*b**2*n*t;    #fraction of particles scattered

#Result
print "fraction of particles scattered is",round(f*10**5,1),"*10**-5"

fraction of particles scattered is 7.5 *10**-5


## Example number 3.3, Page number 48¶

In [9]:
#importing modules
import math
from __future__ import division

#Variable declaration
h=6.626*10**-34;    #planck's constant(Js)
c=3*10**8;    #velocity of light(m/sec)
e=1.6*10**-19;   #conversion factor from J to eV
E=10.5;   #energy(eV)

#Calculation
E=(13.6+E)*e;   #energy of photon(J)
lamda=h*c/E;   #wavelength(m)

#Result
print "wavelength of photon is",round(lamda*10**9,2),"nm"

wavelength of photon is 51.55 nm


## Example number 3.4, Page number 49¶

In [11]:
#importing modules
import math
from __future__ import division

#Variable declaration
k=8.98*10**9;  #value of k(Nm**2/C**2)
e=1.6*10**-19;   #conversion factor from J to eV
n=1;  #assume

#Calculation
PE=-k*(e**2)/(a0*e*n**2);   #potential energy(eV)
E=-13.6/n**2;   #energy(eV)
KE=E-PE;   #kinetic energy(eV)

#Result
print "kinetic energy is",round(KE,1),"/n**2 eV"

kinetic energy is 13.5 /n**2 eV


## Example number 3.6, Page number 51¶

In [14]:
#importing modules
import math
from __future__ import division

#Variable declaration
Mbyme=1836;
lamda=6562.8;    #wavelength for hydrogen(angstrom)

#Calculation
mew_dashbymew=2*(1+Mbyme)/(1+(2*Mbyme));
lamda_dash=lamda/mew_dashbymew;    #wavelength for deuterium(angstrom)

#Result
print "wavelength for deuterium is",int(lamda_dash),"angstrom"

wavelength for deuterium is 6561 angstrom