Physics, asked by satyabdh78pc0kjn, 1 year ago

what are the limitations of Planck's Quantum theory?

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Answered by billu004
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LIMITATIONS OF OLD QUANTUM THEORY

The main shortcomings of the old quantum theory are that it could not

(i) be applied to non-periodic systems.

(ii) explain the spectral lines of system like hydrogen molecule and normal helium atom.

(iii) give any information about the transition probabilities and intensity of spectral lines. .

(iv) explain the process connected with the electron spin and Pauli's exclusion principle.

(v)  explain the dispersion of light.

De-Broglie (1925) and Schrodinger's wave equation satisfied these matter waves.


WAVE PROPERTIES OF MATTER: de-BROGLIE WAVELENGTH

 In 1925, de-Broglie made a suggestion that a moving particle, whatever its nature, has wave properties associated with it and its wavelength is given by

l = h/mv = h/p

where h is Planck's constant, m is the mass and vis the velocity of the particle with which it is moving. This equation is known as de-Broglie relation

or                                             mv = h/l

which states that "the momentum of a moving particle is inversely proportional to the wave length of the wave associated with it."


As the photon travels in free space with velocity of light, c, its momentum is given by

p = mc  = mc2/c =E/c  = hn/c = h/l

or

l = h/p

de-Broglie assumed that this equation should be equally applicable to both the photons of radiation and material particles like electrons. Hence, if  m  is the mass of the particle moving with velocity v, then its momentum p = mv. The wavelength of the wave associated with material particle is

  l =h/mv

This equation is known as de-Broglie wave equation and l called de-Broglie wavelength.

Some of de Broglie's ideas were used by Schrodinger, Dirac, Born, Heisenberg and other physicists which developed into the modem theory of Quantum mechanics.

hope this proves to be useful......

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