ECE/OPTI 414a/514a
Practice Problem Set #3
1. The linewidth of an argon ion laser is 2.25X105 Hz and the emission
center wavelength is 457 nm. For a laser with 2.5 mW of output power and
a beam diameter of 1.25 mm, determine the temperature that a BB would
have to have in order to emit the same number of photons from an equal
area and over the same spectral bandwidth as the laser.
2. Compute the solar energy received over all wavelengths illuminating an
area on the surface of the Earth that is 1.25m1.5 m in a 12 minute time
period. Assume that the illumination is under standard conditions but with
an AM of 1.25. The receiving surface is horizontal.
3. Draw schematic diagrams showing the power and entropy flux
components for a Carnot model, Landsberg model, and a black body
model for power exchange between the sun and a converter in an ambient
environment. Compute the efficiency for each cycle assuming that the Sun
is at 5800K, the ambient temperature is 295K, and the converter is 530K.
For the BB model use the
Q
value from the Carnot model.
4. The plots below show the spectral responsivity of a PV cell and an
approximation to the incident solar spectrum. What is the energy band gap
of the solar cell? If the diameter of the circular cell is 4 inches compute the
short circuit output current from the cell under the illumination conditions
shown. Use an approximate integration technique.
5. Assuming a short circuit current of 2.15A compute the corresponding open
circuit voltage when the PV cell temperature is 22oC and 60oC (i.e. for two
