If Bohr's quantisation postulate (angular momentum = nh/2 $π$ ) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbits of planets around the sun?

Solution

1. Bohr's quantisation postulate is in terms of h. Angular momenta associated with planetary motion are incomparably large relative to h.
2. For example, angular momentum of the earth in its orbital motion is of the order of 10⁷⁰ h. In terms of the Bohr's quantisation postulate, this corresponds to a very large value of n (of the order of 10⁷⁰).
3. For such enormous values of n, the differences in the successive energies and angular momenta of the quantised levels of the Bohr model is so small as compared to the energy levels and angular momenta that one can practically consider as continuous.

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Wave Optics

If Bohr's quantisation postulate (angular momentum = nh/2 $π$ ) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbits of planets around the sun?

Some More Questions From Wave Optics Chapter

The size of the atom in Thomson's model is _________ the atomic size in Rutherford's model. (much greater than/no different from/much less than)

In the ground state of electrons are in stable equilibrium, while in electrons always experience a net force. (Thomson's model/Rutherford's model).

A classical atom based on __________ is doomed to collapse. (Thomson's model/Rutherford's model)

An atom has a nearly continuous mass distribution in a ___ but has a highly non-uniform mass distribution in (Thomson's model/Rutherford's model)

The positively charged part of the atom possesses most of the mass in ___________ (Rutherford's model/both the models).

Suppose you are given a chance to repeat the alpha-particle scattering experiment using a thin sheet of solid hydrogen in place of the gold foil. (Hydrogen is a solid at temperatures below 14 K.) What results do you expect?

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Wave Optics

If Bohr's quantisation postulate (angular momentum = nh/2π) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbits of planets around the sun?

Some More Questions From Wave Optics Chapter

The size of the atom in Thomson's model is _________ the atomic size in Rutherford's model. (much greater than/no different from/much less than)

In the ground state of __________ electrons are in stable equilibrium, while in __________ electrons always experience a net force. (Thomson's model/Rutherford's model).

A classical atom based on __________ is doomed to collapse. (Thomson's model/Rutherford's model)

An atom has a nearly continuous mass distribution in a _____________ but has a highly non-uniform mass distribution in __________ (Thomson's model/Rutherford's model)

The positively charged part of the atom possesses most of the mass in ___________ (Rutherford's model/both the models).

Suppose you are given a chance to repeat the alpha-particle scattering experiment using a thin sheet of solid hydrogen in place of the gold foil. (Hydrogen is a solid at temperatures below 14 K.) What results do you expect?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

If Bohr's quantisation postulate (angular momentum = nh/2 $π$ ) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why then do we never speak of quantisation of orbits of planets around the sun?

In the ground state of electrons are in stable equilibrium, while in electrons always experience a net force. (Thomson's model/Rutherford's model).

An atom has a nearly continuous mass distribution in a ___ but has a highly non-uniform mass distribution in (Thomson's model/Rutherford's model)