PhysicsLAB AP Free Response Question
2002 Form B - B7

An experimenter determines that when a beam of mono-energetic electrons bombards a sample of a pure gas, atoms of the gas are excited if the kinetic energy of each electron in the beam is 3.70 eV or greater.
 (a) Determine the deBroglie wavelength of 3.70 eV electrons.

 (b) Once the gas is excited by 3.70 eV electrons, it emits monochromatic light. Determine the wavelength of this light.

Experiments reveal that two additional wavelengths are emitted if the beam energy is raised to at least 4.90 eV.
 (c) In the space below construct an energy-level diagram consistent with this information and determine the energies of the photons associated with those two additional wavelengths.

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