PhysicsLAB Practice Problems
Absorption and Emission Spectra

Directions: On this worksheet you will practice your knowledge of the properties of absorption and emission spectra as well as several historical experiments leading to their understanding.

Question 1  An experiment is performed on a sample of atoms that have a ground state energy of -18 eV. While the gas was being illuminated with an incandescent light source instrumentation revealed that the sample only absorbed light at a 439 nm wavelength. To what energy level was the ground state sample initially excited?
Question 2  Later, when the illuminating light source was turned off, the sample radiated visible light of 581 nm. State an additional energy level required for the gas present in this sample.
Question 3  At which other wavelength, outside the visible range, must the gas emit radiation to permit it to return to its original ground state?
Question 4  The necessary condition(s) for an absorption spectra to be observed are:
  1. an incandescent light source
  2. a cool gas must be placed between the light source and the spectroscope
  3. all of the lines present in the gas' emission spectra must be included in the wavelengths emitted by the light source
Question 5  A hypothetical atoms has 4 distinct energy states. Assuming all transitions are possible, how many emissions spectral lines can this atom produce?
Question 6  The radiation curve for a 'white hot' incandescent solid peaks in the
Question 7  Two lamps radiate the same amount of energy per second - that is, they have the same power rating. If one lamp emits a red beam and the other a violet beam, which beam contains the greatest number of photons?
Question 8  Which of the following was NOT an outcome of Rutherford's gold foil experiment?
Question 9  Which of the following statement(s) is NOT true about Bohr's atomic model?
  1. He declared that the hydrogen atom can exist, without radiating any energy, in several stable, stationary, states.
  2. To establish orbitals at specified radii, he required that an electron’s angular momentum be quantized.
  3. In his model, radiation would only be absorbed or released when an electron changed from one allowed orbitals to another.
  4. He proved that the unique, discrete spectral lines, previously calculated by Balmer and Rydberg, were incorrect.

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