# Chapter 4 : Laser and Holography¶

## Example number 1 , Page number 81¶

In [1]:
#importing module
import math
from __future__ import division

#Variable declaration
delE=3*1.6*10**-19      #Energy of laser
h=6.63*10**-34          #planck's constant
c=3*10**8               #speed of ligth

#Calculations
lamda=(h*c)/delE/10**-9

#Result
print"Wavelength of radiation= %i nm" %lamda

Wavelength of radiation= 414 nm


## Example number 2 , Page number 81¶

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

#Variable declaration
lamda=6328*10**-10      #wavelength
h=6.63*10**-34          #planck's constant
c=3*10**8               #speed of ligth

#Calculations
E=((h*c)/lamda)/1.6*10**19
Momentum=h/lamda/10**-27

#Result
print"Energy of radiation= %1.2f eV" %E
print"Momentum of electron= %1.3f*10**-27 kgm/s" %Momentum

Energy of radiation= 1.96 eV
Momentum of electron= 1.048*10**-27 kgm/s


## Example number 3 , Page number 82¶

In [3]:
#importing module
import math
from __future__ import division

#Variable declaration
lamda=6730*10**-18      #wavelength
h=6.63*10**-34          #planck's constant
c=3*10**8               #speed of ligth
P=10**-3                #Power of laser

#Calculations
n=(P*lamda)/(h*c)/10**5

#Result
print"Wavelength of radiation= %i*10**15 photons/sec"  %n

Wavelength of radiation= 338*10**15 photons/sec