Chapter 28 Particle nature of radiation

Example 28.1 Page no 801

In [7]:
#Given
l=4950.0*10**-10
h=6.6*10**-34                             #js
c=3*10**8                                 #m/s

#Calculation
E=(h*c/l)/(1.6*10**-19)

#Result
print"Energy of each photon is",E,"eV"

Energy of each photon is 2.5 eV

Example 28.2 Page no 801

In [8]:
#Given
E=6.62                      #J
v=10**12                          #Hz
h=6.62*10**-34

#Calculation
E1=h*v
n=E/(h*v)

#Result
print"Number of photons is",n

Number of photons is 1e+22

Example 28.3 Page no 801

In [38]:
#Given
h=6.62*10**-34                        #js
c=3*10**8                            #m/s
Iev=1.6*10**-19                      #J
V=10**6                               #hz
V1=5890*10**-10                       #m
L=10.0**-10                             #m

#Calculation
E=h*v
E1=E/Iev
A=(h*c)/V1
A1=A/Iev
B=(h*c)/L
B1=B/Iev

#Result
print"(i) The energy of a photon with frequency 1000 Khz is",round(E1*10**3,2),"10**-9","ev" 
print"(ii) The energy of a photon when wavelength is 5890A is",round(A1,2) ,"eV"
print"(iii) The energy of a photon when wavelength is 1 A is", B1,"eV"

(i) The energy of a photon with frequency 1000 Khz is 4.14 10**-9 ev
(ii) The energy of a photon when wavelength is 5890A is 2.11 eV
(iii) The energy of a photon when wavelength is 1 A is 12412.5 eV

Example 28.4 Page no 801

In [45]:
#Given
l=0.66*10**-10                     #m
h=6.62*10**-34                     #Js
c=3*10**8                            #m/s

#Calculation
E=((h*c)/l)/(1.6*10**-19)

#Result
print"(a) Maximum energy of photon is",round(E*10**-3,2),"Kev"
print"(b) To produce electrons of energy 18.81 Kev,accelerating potential of 18.81 KV"

(a) Maximum energy of photon is 18.81 Kev
(b) To produce electrons of energy 18.81 Kev,accelerating potential of 18.81 KV

Example 28.5 Page no 801

In [60]:
#Given
E=10.2*10**9                         #ev
h=6.62*10**-34
c=3*10**8

#Calculation
E1=(E/2.0)*(1.6*10**-19)
l=(h*c)/E1

#Result
print"Wavelength is",round(l*10**16,3),"10**-16"

Wavelength is 2.434 10**-16

Example 28.6 Page no 802

In [75]:
#Given
L=3500.0*10**-10                  #m
h=6.62*10**-34
c=3*10**8

#Calculation
Hv=h*c/(L*(1.6*10**-19))

#Result
print"Energy of incident light is", round(Hv,3),"eV \nMetal B will yield photoelectrons."

Energy of incident light is 3.546 eV 
Metal B will yield photoelectrons.

Example 28.7 Page no 802

In [83]:
#Given
l=6000.0*10**-10             #m
h=6.62*10**-34                    #Js
e=1.6*10**-19
c=3*10**8

#Calculation
v0=c/l
w=(h*v0)/e

#Result
print"(i) Threshold frequency is", v0,"Hz"
print"(ii) Work function is",round(w,3),"eV"

(i) Threshold frequency is 5e+14 Hz
(ii) Work function is 2.069 eV

Example 28.8 Page no 802

In [90]:
#Given
w=1.2*1.6*10**-19
l=5000.0*10**-10
c=3*10**8
h=6.62*10**-34
e=1.6*10**-19

#Calculation
A=((h*c)/l)-w
V0=A/e

#Result
print"Stopping potential is", round(V0,2),"V"

Stopping potential is 1.28 V

Example 28.9 Page no 802

In [104]:
#Given
h=6.6*10**-34                     #Js
e=1.6*10**-19
l=500.0*10**-9                    #m

#Calculation
w=2*e
l0=(h*c)/w
E=((h*c)/l)-w
v0=E/e

#Result
print"(i) The threshold wavelength is", l0*10**9,"nm"
print"(ii) Maximum energy is",E*10**19,"*10**-19 J"
print"(iii) The stopping potential is",v0,"V"

(i) The threshold wavelength is 618.75 nm
(ii) Maximum energy is 0.76 *10**-19 J
(iii) The stopping potential is 0.475 V

Example 28.10 Page no 802

In [109]:
#Given
V0=1.3
l=2271*10**-10
h=6.62*10**-34
e=1.6*10**-19
c=3*10**8

#Calculation
w=(h*c/l)-(V0*e)
l0=(h*c)/w

#Result
print"Work function of metal is", round(l0*10**10,0),"A"

Work function of metal is 2980.0 A

Example 28.11 Page no 803

In [115]:
#Given
h=6.62*10**-34
c=3*10**8
l=640.2*10**-9
e=1.6*10**-19
V0=0.54
l1=427.2*10**-9

#Calculation
w=(h*c/l)-(e*V0)
v0=(((h*c)/l1)-w)/e

#Result
print"New stopping voltage is", round(v0,3),"V"

New stopping voltage is 1.507 V

Example 28.12 Page no 803

In [121]:
#Given
l=5600.0*10**-10                      #m
h=6.625*10**-34
c=3*10**8
a=5

#Calculation
E=h*c/l
n=a/E

#Result
print"Number of visible light photon is", round(n*10**-19,2)*10**-19

Number of visible light photon is 1.41e-19

Example 28.13 Page no 803

In [132]:
#Given
E=10**4                        #W
l=500.0                    #m
h=6.62*10**-34
A=0.4*10**-14                #m**2
i=10**-10                     #W/m**2
v=6*10**14

#Calculation
E1=E*l/(h*c)
E2=h*v
n=A/E2

#Result
print"(i) Number of photons emitted is",round(E1*10**-31,3)*10**31
print"(ii) Number of photons is", round(n*10**-4,0),"*10**4"

(i) Number of photons emitted is 2.518e+31
(ii) Number of photons is 1.0 *10**4

Example 28.14 Page no 803

In [145]:
#Given
A=2*10**-4                        #m**2
An=10.0**-20
n1=5
i=10**-5                           #W/m**2

#Calculation
n=(A*n1)/An
E=i*A
E1=(E/n)/e
t=2/E1

#Result
print"Time required for the photoelectric emission is",t*10**-7,"*10**7 S"

Time required for the photoelectric emission is 1.6 *10**7 S