Bohr’s Model and Physics of Atom Physics - Bohr’s Model and Physics of Atom

In a laser tube, all the photons:

1. Have same wavelength.
2. Have same energy.
3. Move in same direction.
4. Move with same speed.

Three photons coming from excited atomic-hydrogen sample are picked up. Their energies are 12.1eV, 10.2 eV and 1.9eV. These photons must come from:

1. A single atom.
2. Two atoms.
3. Three atoms.
4. Either two atoms or three atoms.

An electron with kinetic energy 5eV is incident on a hydrogen atom in its ground state. The collision:

1. Must be elastic.
2. May be partially elastic.
3. Must be completely inelastic.
4. May be completely inelastic.

When a photon stimulates the emission of another photon, the two photons have:

1. Same energy.
2. Same direction.
3. Same phase.
4. Same wavelength.
5. All of the above

In a laboratory experiment on emission from atomic hydrogen in a discharge tube, only a small number of lines are observed whereas a large number of lines are present in the hydrogen spectrum of a star. This is because in a laboratory:

1. The amount of hydrogen taken is much smaller than that present in the star.
2. The temperature of hydrogen is much smaller than that of the star.
3. The pressure of hydrogen is much smaller than that of the star.
4. The gravitational pull is much smaller than that in the star.

A gas of hydrogen-like ions is prepared in a particular excited state A. It emits photons having wavelength equal to the wavelength of the first line of the Lyman series together with photons of five other wavelengths. Identify the gas and find the principal quantum number of the state A.

Evaluate Rydberg constant by putting the values of the fundamental constants in its expression.

Find the maximum Coulomb force that can act on the electron due to the nucleus in a hydrogen atom.

Suppose, in certain conditions only those transitions are allowed to hydrogen atoms in which the principal quantum number n changes by 2. (a) Find the smallest wavelength emitted by hydrogen. (b) List the wavelength emitted by hydrogen in the visible range (380nm to 780nm).

The average kinetic energy of molecules in a gas at temperature T is 1.5kT. Find the temperature at which the average kinetic energy of the molecules of hydrogen equals the binding energy of its atoms. Will hydrogen remain in molecular from at this temperature? Take k = 8.62 × 10^-5eVK^-1.

Find the temperature at which the average thermal kinetic energy is equal to the energy needed to take a hydrogen atom from its ground state to n = 3 state. Hydrogen can now emit red light of wavelength 653.1nm. Because of Maxwellian distribution of speeds, a hydrogen sample emits red light at temperatures much lower than that obtained from this problem. Assume that hydrogen molecules dissociate into atoms.

A hydrogen atom in state n = 6 makes two successive transitions and reaches the ground state. In the first transition a photon of 1.13eV is emitted. (a) Find the energy of the photon emitted in the second transition (b) What is the value of n in the intermediate state?

Average lifetime of a hydrogen atom excited to n = 2 state is 10^-8s. Find the number of revolutions made by the electron on the average before it jumps to the ground state.

Find the radius and energy of a He⁺ ion in the states (a) n = 1, (b) n = 4 and (c) n = 10.

A hydrogen atom in ground state absorbs a photon of ultraviolet radiation of wavelength 50nm. Assuming that the entire photon energy is taken up by the electron with what kinetic energy will the electron be ejected?

When white radiation is passed through a sample of hydrogen gas at room temperature, absorption lines are observed in Lyman series only. Explain.

Consider a neutron and an electron bound to each other due to gravitational force. Assuming Bohr's quantization rule for angular momentum to be valid in this case, derive an expression for the energy of the neutron-electron system.

A parallel beam of light of wavelength 100nm passes through a sample of atomic hydrogen gas in ground state. (a) Assume that when a photon supplies some of its energy to a hydrogen atom, the rest of the energy appears as another photon. Neglecting the light emitted by the excited hydrogen atoms in the direction of the incident beam, what wavelengths may be observed in the transmitted beam? (b) A radiation detector is placed near the gas to detect radiation coming perpendicular to the incident beam. Find the wavelengths of radiation that may be detected by the detector.

A group of hydrogen atoms are prepared in n = 4 states. List the wavelength that are emitted as the atoms make transitions and return to n = 2 states.

We have stimulated emission and spontaneous emission. Do we also have stimulated absorption and spontaneous absorption?