answer the multiple choice questions and show some work. Please make sure to sho

Question

answer the multiple choice questions and show some work. Please make sure to show the proper equations used.

1) The number of states in a subshell with orbital quantum number I=3 is: A) 2 B) 3 C) 7 D) 9 E) 14 2) No state in an atom can be occupied by more than one electron. This is most closely related to: A) the wave nature of matter B) the finite value for the speed of light C) the Bohr magneton D) the Pauli exclusion principle E) the Einstein -de Haas effect 3) Photons in a laser beam are produced by: A) transitions from a metastable state B) transitions from a state that decays rapidly C) splitting of other photons D) pumping E) reflection from mirrors 4) Population inversion is important for the generation of a laser beam because it assures that: A) spontaneous emission does not occur more often than stimulated emission B) photons do not split too rapidly C) more photons are emitted than are absorbed D) photons do not collide with each other E) photons do not make upward transitions 5) The purpose of the mirrors at the ends of a helium -neon laser is: A) to assure that no laser light leaks out B) to increase the number of stimulated emissions C) to absorb some of the photons D) to keep the light used for pumping inside the laser E) to double the effective length of the laser

Explanation / Answer

1) E

Reason- one electron per |n,l,m,s> state
for l=3, there are 7 possible values for m, with two spin states each = 14 total.

2) D- The pauli Exclusion principle

Reason: The Pauli exclusion principle states that, 2 identical fermions(particles with half-integer spin), cannot occupy the same quantum state simultaneously.

3) B; Reason: When electrons are excited from a lower to a higher energy level, they will not stay that way forever. The electrons in an excited state may decay to a lower energy state which is not occupied, according to a particular time constant characterizing that transition. When such electrons decay without external influence, it emits photons.

4) C); Reason: The gain medium of a laser is normally a material of controlled purity, size, concentration, and shape, which amplifies the beam by the process of stimulated emission described above. This material can be of any state: gas, liquid, solid, or plasma. The gain medium absorbs pump energy, which raises some electrons into higher-energy ("excited") quantum states. Particles can interact with light by either absorbing or emitting photons. Emission can be spontaneous or stimulated. In the latter case, the photon is emitted in the same direction as the light that is passing by. When the number of particles in one excited state exceeds the number of particles in some lower-energy state, population inversion is achieved and the amount of stimulated emission due to light that passes through is larger than the amount of absorption.

5) B); Reason: The optical cavity of the laser usually consists of two concave mirrors or one plane and one concave mirror, one having very high (typically 99.9%) reflectance and the output coupler mirror allowing approximately 1% transmission. The mirrors at each end of the cavity, makes the laser reflect back upon itself, gaining more power in each pass than is lost due to transmission through the mirrors and difraction.

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