Worksheet: Lasers

In this worksheet, we will practice describing the components of a laser and how lasers produce coherent light.

Q1:

Which of the following statements correctly describes the spontaneous emission of photons from excited atoms?

  • ASpontaneous emission is a process where a high-energy photon collides with an atom and scatters through a large angle.
  • BSpontaneous emission is a process where a photon collides with an electron in an atom, moving it to a higher energy level.
  • CSpontaneous emission is a process where an incident photon causes an electron in a higher energy level to fall to a lower energy level, releasing a second photon with the same frequency and phase as the first.
  • DSpontaneous emission is a process where a low-energy photon collides with an atom and scatters through a small angle.
  • ESpontaneous emission is a process where an electron in a higher energy level falls to a lower energy level, emitting a photon without having interacted with any other particles.

Q2:

Which of the following statements is the correct definition of population inversion?

  • APopulation inversion is the process of raising electrons in the atoms of the gain medium of a laser to excited states using incoherent light from nonlaser light sources.
  • BPopulation inversion is the process of atoms in excited states emitting photons of the same phase and direction as an incident photon.
  • CPopulation inversion is when the number of atoms in the gain medium of a laser that are in excited states is greater than the number of atoms that are in unexcited states.
  • DPopulation inversion is when the number of atoms in the gain medium of a laser that are in unexcited states is greater than the number of atoms that are in excited states.

Q3:

Which of the following statements correctly describes the stimulated emission of photons from excited atoms?

  • AStimulated emission is a process where a low-energy photon collides with an atom and scatters through a small angle.
  • BStimulated emission is a process where a photon collides with an electron in an atom, moving it to a higher energy level.
  • CStimulated emission is a process where an electron in a higher energy level falls to a lower energy level, emitting a photon without having interacted with any other particles.
  • DStimulated emission is a process where an incident photon causes an electron in a higher energy level to fall to a lower energy level, releasing a second photon with the same frequency and phase as the first.
  • EStimulated emission is a process where a high-energy photon collides with an atom and scatters through a large angle.

Q4:

In order for a laser to produce laser light, the number of atoms in the gain medium in excited states must be greater than the number of atoms in unexcited states. What is the term for this phenomenon?

  • APopulation inversion
  • BDivergence
  • CResonance
  • DPolarization
  • ECollimation

Q5:

The table shows five different gain media that can be used in lasers.

Gain Medium Laser Type Wavelength
Nitrogen Gas 337 nm
Carbon monoxide Gas 2.60 μM
Copper Metal vapor 511 nm
Gold Metal vapor 627 nm
Indium gallium nitrate Semiconductor 400 nm

Which gain medium produces the highest-energy photons?

  • ANitrogen
  • BIndium gallium nitrate
  • CCopper
  • DGold
  • ECarbon monoxide

Which gain medium produces the lowest-energy photons?

  • ACarbon monoxide
  • BIndium gallium nitrate
  • CGold
  • DCopper
  • ENitrogen

Q6:

The figure shows a cross section of the construction of a laser. What term is given to the component labeled X?

  • AThe cathode
  • BThe gain medium
  • CThe output coupler
  • DThe anode
  • EThe high reflector

Q7:

The figure shows a cross section of the construction of a laser. Which of the components A and B is the output coupler?

  • AComponent B
  • BComponent A

Q8:

The figure shows a cross section of the construction of a laser. Through which end of the laser End A and End B will the laser light escape?

  • AEnd A
  • BEnd B

Q9:

The figure shows a cross section of the construction of a laser. Which of the components A and B is the high reflector?

  • AComponent B
  • BComponent A

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