2: Particle nature of radiation

Example number 2.1, Page number 28

In [2]:
#importing modules
import math
from __future__ import division

#Variable declaration
h=6.626*10**-34;    #planck's constant(Js)
new=100*10**6;    #frequency(Hz)
P=100*10**3;    #power(watt)

#Calculation
E=h*new;    #quantum of energy(J)
n=P/E;    #number of quanta emitted(per sec)

#Result
print "number of quanta emitted is",round(n/10**29,2),"*10**29 per sec"

number of quanta emitted is 15.09 *10**29 per sec

Example number 2.2, Page number 31

In [6]:
#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)
lamda=400*10**-9;    #wavelength(m)
e=1.6*10**-19;   #conversion factor from J to eV
w0=2.28;    #work function(eV)
m=9.1*10**-31;    #mass of electron(kg)

#Calculation
E=h*c/(lamda*e);    #energy(eV)
KEmax=E-w0;    #maximum kinetic energy(eV)
v2=2*KEmax*e/m;  
v=math.sqrt(v2);   #velocity(m/s)

#Result
print "maximum kinetic energy is",round(KEmax,3),"eV"
print "velocity of photoelectrons is",round(v/10**5,2),"*10**5 m/s"

maximum kinetic energy is 0.826 eV
velocity of photoelectrons is 5.39 *10**5 m/s

Example number 2.3, Page number 31

In [8]:
#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)
lamda=2000*10**-10;    #wavelength(m)
e=1.6*10**-19;   #conversion factor from J to eV
w0=4.2;    #work function(eV)

#Calculation
lamda0=h*c/(w0*e);   #cut off wavelength(m)
E=h*c/(lamda*e);    #energy(eV)
sp=E-w0;    #stopping potential(eV)

#Result
print "cut off wavelength is",int(lamda0*10**10),"angstrom"
print "stopping potential is",round(sp,2),"V"

cut off wavelength is 2958 angstrom
stopping potential is 2.01 V

Example number 2.4, Page number 33

In [11]:
#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)
lamda=0.2*10**-9;    #wavelength(m)

#Calculation
p=h/lamda;    #momentum(kg m/s)
m=p/c;   #effective mass(kg)

#Result
print "momentum is",round(p*10**24,1),"*10**-24 kg m/s"
print "effective mass is",round(m*10**32,1),"*10**-32 kg"

momentum is 3.3 *10**-24 kg m/s
effective mass is 1.1 *10**-32 kg

Example number 2.5, Page number 35

In [18]:
#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)
lamda=0.15;    #wavelength(nm)
m0=9.1*10**-31;    #mass of electron(kg)
theta1=0;   #scattering angle1(degrees)
theta2=90;   #scattering angle2(degrees)
theta3=180;   #scattering angle3(degrees)

#Calculation
theta1=theta1*math.pi/180;   #scattering angle1(radian)
theta2=theta2*math.pi/180;   #scattering angle2(radian)
theta3=theta3*math.pi/180;   #scattering angle3(radian)
lamda_dash1=lamda+(h*(1-math.cos(theta1))/(m0*c));   #wavelength at 0(nm)
lamda_dash2=lamda+(10**9*h*(1-math.cos(theta2))/(m0*c));   #wavelength at 90(nm)
lamda_dash3=lamda+(10**9*h*(1-math.cos(theta3))/(m0*c));   #wavelength at 180(nm)

#Result
print "wavelength at 0 degrees is",lamda_dash1,"nm"
print "wavelength at 90 degrees is",round(lamda_dash2,3),"nm"
print "wavelength at 180 degrees is",round(lamda_dash3,3),"nm"

wavelength at 0 degrees is 0.15 nm
wavelength at 90 degrees is 0.152 nm
wavelength at 180 degrees is 0.155 nm

Example number 2.6, Page number 36

In [21]:
#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=2*0.511*10**6;   #rest energy(eV)

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

#Result
print "wavelength of photon is",round(lamda*10**12,2),"*10**-12 m"

wavelength of photon is 1.22 *10**-12 m