# 7: Wave and Quantum Mechanics¶

## Example number 7.1, Page number 192¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
h = 6.625*10**-34;          #planck's constant(J sec)
m1 = 6*10**24;             #mass of earth(kg)
v1 = 3*10**4;              #orbital speed(m/sec)
m2 = 10**-30;              #mass of electron(kg)
v2 = 10**6;                #velocity of electron(m/sec)

#Calculation
lamdaE = h/(m1*v1);       #wavelength of a wave(m)
lamdae = h/(m2*v2);         #wavelength of electron(m)

#Result
print "wavelength of a wave is",round(lamdaE/1e-63,2),"*10**-63 m"
print "wavelength of electron is",lamdae,"m"

wavelength of a wave is 3.68 *10**-63 m
wavelength of electron is 6.625e-10 m


## Example number 7.2, Page number 193¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
m = 1;        #mass of particle(g)
v = 100;       #velocity of particle(m/sec)
h = 6.625*10**-34;          #planck's constant(J sec)

#Calculation
m = m*10**-3;        #mass of particle(kg)
lamda = h/(m*v);      #wavelength of particle(m)

#Result
print "wavelength of particle is",lamda,"m"

wavelength of particle is 6.625e-33 m


## Example number 7.3, Page number 193¶

In :
#importing modules
import math
from __future__ import division

#Variable declaration
V = 200;      #potential difference(V)

#Calculation
lamda = 12.28/math.sqrt(V);       #de Broglie wavelength(angstrom)
lamda = math.ceil(lamda*10**4)/10**4;   #rounding off to 4 decimals

#Result
print "de Broglie wavelength of electron is",lamda,"angstrom"
print "answer given in the book varies due to rounding off errors"

de Broglie wavelength of electron is 0.8684 angstrom
answer given in the book varies due to rounding off errors

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