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 an electron in a higher energy level falls to a lower energy level, emitting a photon without having interacted with any other particles.
  • BSpontaneous emission is a process where a high-energy photon collides with an atom and scatters through a large angle.
  • CSpontaneous emission is a process where a low-energy photon collides with an atom and scatters through a small angle.
  • DSpontaneous 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.
  • ESpontaneous emission is a process where a photon collides with an electron in an atom, moving it to a higher energy level.

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 unexcited states is greater than the number of atoms that are in excited states.
  • DPopulation 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.

Q3:

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

  • AStimulated 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.
  • BStimulated 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.
  • CStimulated emission is a process where a photon collides with an electron in an atom, moving it to a higher energy level.
  • DStimulated emission is a process where a low-energy photon collides with an atom and scatters through a small angle.
  • 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?

  • ADivergence
  • BCollimation
  • CPolarization
  • DResonance
  • EPopulation inversion

Q5:

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

Gain MediumLaser TypeWavelength
NitrogenGas337 nm
Carbon monoxideGas2.60 μm
CopperMetal vapor511 nm
GoldMetal vapor627 nm
Indium gallium nitrideSemiconductor400 nm

Which gain medium produces the highest-energy photons?

  • AIndium gallium nitride
  • BCarbon monoxide
  • CGold
  • DCopper
  • ENitrogen

Which gain medium produces the lowest-energy photons?

  • ACarbon monoxide
  • BIndium gallium nitride
  • 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 gain medium
  • BThe high reflector
  • CThe output coupler
  • DThe anode
  • EThe cathode

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 A
  • BComponent B

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 B
  • BEnd A

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 A
  • BComponent B

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