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प्रश्न
Answer in brief.
State the postulates of Bohr’s atomic model.
उत्तर
The postulates of Bohr's atomic model (for the hydrogen atom):
- The electrons revolve around the nucleus in circular orbits. This is the same assumption as in Rutherford’s model and the centripetal force necessary for the circular motion is provided by the electrostatic force of attraction between the electron and the nucleus.
- The radius of the orbit of an electron can only take certain fixed values such that the angular momentum of the electron in these orbits is an integral multiple of `"h"/(2π)`, h being Planck’s constant. Such orbits are called stable orbits or stable states of the electrons and electrons in these orbits do not emit radiation as is demanded by classical physics. Thus, different orbits have different and definite values of angular momentum and therefore, different values of energy.
- An electron can make a transition from one of its orbits to another orbit having lower energy. In doing so, it emits a photon of energy equal to the difference in its energies in the two orbits.
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संबंधित प्रश्न
Answer in one sentence:
Name the element that shows the simplest emission spectrum.
According to Bohr's second postulate, the angular momentum of the electron is the integral multiple of `h/(2pi)`. The S.I unit of Plank constant h is the same as ______
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State Bohr's second postulate for the atomic model. Express it in its mathematical form.
State any two limitations of Bohr’s model for the hydrogen atoms.
Using the expression for the radius of orbit for the Hydrogen atom, show that the linear speed varies inversely to the principal quantum number n the angular speed varies inversely to the cube of principal quantum number n.
Which of the following series of transitions in the spectrum of hydrogen atom falls in ultraviolet region?
The radius of electron's second stationary orbit in Bohr's atom is R. The radius of the third orbit will be ______
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The wavelength of the first line in Balmer series in the hydrogen spectrum is 'λ'. What is the wavelength of the second line in the same series?
With the increase in principal quantum number, the energy difference between the two successive energy levels ____________.
What is the de Broglie wavelength of an electron of energy 180 eV?
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In Bohr's model of hydrogen atom, the period of revolution of the electron in any orbit is proportional to ______.
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In hydrogen emission spectrum, for any series, the principal quantum number is n. Corresponding maximum wavelength λ is ______.
(R = Rydberg's constant)
In Bohr's model of hydrogen atom, which of the following pairs of quantities are quantized?
An electron makes a transition from an excited state to the ground state of a hydrogen like atom. Out of the following statements which one is correct?
The de-Broglie wavelength of an electron in 4th orbit is ______.
(r = radius of 1st orbit)
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What is the mathematical formula for the third postulate of Bohr's atomic model?
An electron of mass m and charge e initially at rest gets accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t ignoring relativistic effects is ______.
The triply ionised beryllium (Be+++) has the same electron orbital radius as that of the ground state of the hydrogen atom. The energy state (n) of triply ionised beryllium is ______.
(Z for beryllium = 4)
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Calculate the energy of the electron in the ground state of the hydrogen atom. Express it in joule and in eV.
Show that the angular speed of an electron in the nth Bohr orbit is w = `(πme^4)/(2ε_0^2h^3n^3)` and the corresponding frequency of the revolution of the electron is f = `(me^4)/(4ε_0^2h^3n^3)`.
Compute the shortest and the longest wavelength in the Lyman series of hydrogen atom.
Find the ratio of radius of 1st Bohr orbit to that of 4th Bohr orbit.
