# Chapter 17 Quantum theory¶

## Example 17.1 Page no 284¶

In :
#given
w=4000.0                                       #Wavelength of the light in Angstrom units
wf=2.25                                      #Work function of potassium in eV
m=(9.1*10**-31)                              #Mass of the electron in kg
v=(3*10**8)                                  #Velocity of light in m/s
c=(1.6*10**-19)                              #Charge of the electron in coloumbs
h=6.626*10**-34                              #Plancks constant in Js

#Calculations
E=(h*v)/(w*10**-10*c)
KE=(E-wf)

#Output
print"Maximum kinetic energy of photoelectron is ",round(KE,3),"eV"

Maximum kinetic energy of photoelectron is  0.856 eV


## Example 17.2 Page no 284¶

In :
#given
wf=1.9                                                 #Workfunction of the material in eV
w=3000                                                 #Wavelength of the light in Angstrom units
v=(3*10**8)                                            #Velocity of light in m/s
c=(1.6*10**-19)                                        #Charge of the electron in coloumbs
h=6.626*10**-34                                        #Plancks constant in Js

#Calculations
V=(1/c)*(((h*v)/(w*10**-10))-(wf*c))

#Output
print"Stopping potential is ",round(V,2),"V"

Stopping potential is  2.24 V


## Example 17.3 Page no 284¶

In :
#given
V=(70*10**3)                                          #Accelerating potential in V
v=(3*10**8)                                           #Velocity of light in m/s
c=(1.6*10**-19)                                       #Charge of the electron in coloumbs
h=6.626*10**-34                                       #Plancks constant in Js

#Calculations
lmin=((h*v)/(c*V))/10**-9

#Output
print"Shortest wavelength of X-rays produced is ",round(lmin,4),"mm"

Shortest wavelength of X-rays produced is  0.0177 mm


## Example 17.4 Page no 284¶

In :
#given
w1=2                                      #Wavelength in Angstrom
Z1=24                                     #Target one
Z2=42.0                                   #Target two
a=1                                       #Constant value

#Calculations
w2=w1*(Z1-a)**2/(Z2-a)**2

#Output
print"Wavelength is ",round(w2,2),"Angstrom"

Wavelength is  0.63 Angstrom


## Example 17.5 Page no 284¶

In :
#given
w=3                                              #Wavelength of the light in Angstrom
v=(3*10**8)                                      #Velocity of light in m/s
h=6.626*10**-34                                  #Plancks constant in Js
q=40                                             #Scattering angle in degrees
m=(9.11*10**-31)                                 #Mass of electron in kg
c=(1.6*10**-19)                                  #Charge of the electron in coloumbs

#Calculations
import math
dl=(h/(m*v))*(1-math.cos(q*3.14/180.0))/10.0**-10
l=(w+dl)

#Output
print"Wavelength of scattered X-rays is ",round(l,4),"Angstrom"

Wavelength of scattered X-rays is  3.0057 Angstrom