Page 2 - LN 5

This is for light but for other particles v˂˂˂c, so above equation can be written as

h
 
mv

 Significance of de Broglie equation :

 Although the de Broglie equation is applicable to all material
objects but it has significance only in case of microscopic

particles.
 It has no significance in our day today life.

 Calculation of de-Broglie wavelength of the electron from the potential
applied to accelerate it.

If accelerating potential V is applied to an electron beam, the energy
acquired by the electron is expressed in electron volt (eV) which is
equal to charge on the electron in coulombs x potential applied in

volts. This energy becomes kinetic energy of the electron.
1 mv  eV
2
2

2 eV
v 
m
h
 
mv
h m
  
m 2 eV
h
 
2 meV

-34
2 -1
Substituting the values of h=6.626 x 10 kg m s
-31
m= 9.11 x 10 kg
-19
e = 1.602 x 10 C
We have

. 1 226 10  9
  m
V
 Derivation of Bohr's postulate of angular momentum from

de Broglie equation :
According to Bohr's model, the electron revolves around the

nucleus in circular orbits. According to de Broglie concept,
the electron is not only a particle but has a wave character.

So in order that the wave may be completely in phase, the