# Chapter 3: De Broglie's Postulate - Wavelike Properties of Particles¶

## Example 3.1, Page 56¶

In [1]:
import math

#Variable declaration
m=1#in kg
h=6.63*10**-34#Joule-sec
v=10#in m/sec

#Calculations & Results
lamda=h/(m*v)
print "Part(a)\n De broglie wavelength for v=10m/sec %.1e m"%lamda

#For KE=100ev
m=9.1*10**-31
K=100*1.6*10**-19#in Joules
lamda=h/math.sqrt(2*m*K)
print "\nPart(b)\n De broglie wavelength is %.1e m"%lamda

Part(a)
De broglie wavelength for v=10m/sec 6.6e-35 m

Part(b)
De broglie wavelength is 1.2e-10 m


## Example 3.2, Page 60¶

In [2]:
#Variable declaration
h=6.63*10**-34#Joule-sec
v=1.635*10**3#m/s
M=4*10**-3#in kg/mole
No=6.02*10**23#atom/mole

#Calculations & Results
m=M/No
print "Mass of Helium atom is %.2e kg"%m
lamda=h/(m*v)
print "De broglie wavelength is %.1e m"%lamda

Mass of Helium atom is 6.64e-27 kg
De broglie wavelength is 6.1e-11 m


## Example 3.3, Page 69¶

In [3]:
import math

#Calculations & Results
#For electron
m1=9.1*10**-31#in kg
v=300#in m/s
h=6.6*10**-34#in joule-sec
p1=m1*v#delta v
delta_p1=.0001*p1#m*delata_v in kg-m/sec
delta_x1=(h)/(4*math.pi*delta_p1)
print "Position of electron %.e  m"%delta_x1

#For bullet
m2=0.05#in kg
p2=m2*v
delta_p2=0.0001*p2#in kg-m/s
delta_x2=(h)/(4*math.pi*delta_p2)
print "Position of bullet %.e  m"%delta_x2

Position of electron 2e-03  m
Position of bullet 4e-32  m


## Example 3.5, Page 75¶

In [4]:
import math

#Calculations & Results
lamda=5890*10**-8#in cm
c=3*10**10#in cm/s
v=c/lamda
del_v=8*10**6#per s
x=del_v/v
h=4.14*10**-15#in ev-sec
print "Part(b)\nFractional width of either line(del_v/v) %.1e  "%x

#Calculate uncertainty
del_t=10**-8
del_e=(h)/(4*math.pi*del_t)
print "\nPart(b)\nUncertainty is %.1e ev "%del_e

Part(b)
Fractional width of either line(del_v/v) 1.6e-08

Part(b)
Uncertainty is 3.3e-08 ev