# Chapter 6 : Photoelectric Effect¶

## Example 6.1 Page No : 191¶

In [1]:

import math

# Variables
h = 6.62*10**-34;      #Planck's constant(in m2*kg/s)
c = 3*10**8;           #speed of light (in m/s)
e = 1.6*10**-19;       #electron charge(in coulomb)
Wavelength_1 = 2300*10**-10;
Wavelength_2 = 1800*10**-10;

# Calculation
W = h*c/Wavelength_1;			#Work function
E_in = h*c/Wavelength_2;
E = E_in-W;			#kinetic energy of the ejected electron(in Joules)
E_1 = E/e;			#kinetic energy of the ejected electron(in eV)

# Results
print 'kinetic energy of the ejected electron in = %.1f eV'%E_1

kinetic energy of the ejected electron in = 1.5 eV


## Example 6.2 Page No : 191¶

In [2]:

import math

# Variables
h = 6.625*(10**(-34));	#Planck's constant(in m2*kg/s)
c = 3*10**8;			#speed of light (in m/s)
e = 1.602*10**-19;		#electron charge(in coulomb)
W = 2.3;			    #work (in eV)

# Calculation
W_1 = W*e;			#work (in joules)
v_o = W_1/h;			#threshold frequency(in Hz)
Wavelength = (h*c/W_1)/10**(-10);			#Wavelength in Angstrom

# Results
print 'threshold frequency(Hz) = %.2e'%v_o
print 'Wavelength in %.0f Angstrom'%(round(Wavelength,-1))

threshold frequency(Hz) = 5.56e+14
Wavelength in 5390 Angstrom


## Example 6.3 Page No : 192¶

In [6]:


import math

# Variables
h = 6.625*(10**(-34));			#Planck's constant(in m2*kg/s)
c = 3*10**8;			#speed of light (in m/s)
e = 1.602*10**-19;			#electron charge(in coulomb)

# Calculation
wavelength = 6800*10**-10;			#wavelength of radiation
v_o = c/wavelength;			#frequency
W = h*v_o;			#Work function

# Results
print 'threshold frequency in = %.2e Hz'%v_o
print 'work function of metal in = %.2e joule'%W

threshold frequency in = 4.41e+14 Hz
work function of metal in = 2.92e-19 joule


## Example 6.4 Page No : 192¶

In [3]:

import math

# Variables
h = 6.625*(10**(-34));			#Planck's constant(in m2*kg/s)
c = 3.*10**8;			#speed of light (in m/s)

# Calculation
L_r  = 150*8./100;			#Lamp rating(in joule)
wavelength = 4500.*10**-10;			#in meter
W = h*c/wavelength;			#work function
N = L_r/W;			#number of photons emitted by lamp per second

# Results
print 'number of photons emitted by lamp per second = %.1e'%N

number of photons emitted by lamp per second = 2.7e+19


## Example 6.5 Page No : 193¶

In [1]:

import math

# Variables
h = 6.6*(10**(-34));			#Planck's constant(in m2*kg/s)
c = 3*10**8;			#speed of light (in m/s)
e = 1.6*10**-19;			#electron charge(in coulomb)
W = 2.24;			#work function(in eV)

# Calculation
W_1 = W*e;			#work function(in joule)
v = (W_1/h)*10**-10;			#frequency
wavelength = c/v;			#region of electrons spectrum is less than(in angstrom)

# Results
print 'region of electrons spectrum is less than %d angstrom'%round(wavelength,-1)

region of electrons spectrum is less than 5520 angstrom


## Example 6.6 Page No : 193¶

In [7]:

import math

# Variables
h = 6.625*(10**(-34));			#Planck's constant(in m2*kg/s)
c = 3*10**8;			#speed of light (in m/s)

# Calculation
v = 440*10**3;			#Operating frequency
E = h*v;			#Energy of each electron
N = P_o/E;			#Number of photons emitted/sec

# Results

Number of photons emitted/sec by radio receiver = 3.4e+31


## Example 6.7 Page No : 193¶

In [12]:


import math

# Variables
W_t = 4.52;			#Work function for tungesten(in eV)
W_b = 2.5;			#Work function for barrium(in eV)
h = 6.62*(10**(-34));			#Planck's constant(in m2*kg/s)
c = 3*10**8;			#speed of light (in m/s)

# Calculation
e = 1.6*10**-19;			#electron charge(in coulomb)
W_T = W_t*e;			#Work function for tungesten(in Joule)
W_B = W_b*e;			#Work function for barrium(in Joule)
Wavelength_T = (h*c/W_T)*10**10;			#wavelength of light which can just eject electron from tungsten
Wavelength_B = (h*c/W_B)*10**10;			#wavelength of light which can just eject electron from barrium

# Results
print 'wavelength of light which can just eject electron from tungsten in = %.0f Angstrom'%Wavelength_T
print 'wavelength of light which can just eject electron from barrium in = %.0f Angstrom'%Wavelength_B

wavelength of light which can just eject electron from tungsten in = 2746 Angstrom
wavelength of light which can just eject electron from barrium in = 4965 Angstrom