You are given a piece of material (you suspect it's a semiconductor but are not sure) and know nothing about it (except that it looks transparent to the eye).

a. What is the minimum band gap energy that you expect this material to have?
b. Describe an experiment to determine its conductivity. Be specific about details: set up, what equipment is used to measure each variable, and plot the data you expect to get.
c. Describe an experiment (or set of experiments) to determine its energy gap, electron affinity, and ionization potential. Be specific as in b.
d. From the above experiments, how can you be sure it's a semiconductor and not a metal?

Steam in a heating system flows through tubes whose outer radius is 2.5 cm and whose walls are maintained at a temperature of 180 °c . circular aluminum alloy 2024-t6 fins ( k= 186 wm. k) of outer radius 3 cm and constant thickness 1 mm are attached to the tube. the space between the fins is 3 mm and thus there are 250 fins per meter of tube length. heat is transferred to the surrounding air at too-25 °c, with a heat transfer coefficient of 40 w/m2. k. manufacturer a claims that this system is rated at 3.5 kw per meter of tube length. if the fins are an integral part of the steam tube, find the heat transfer rate in kw for a 1-m length of tube. is manufacturer a's claim valid? compare the heat transfer rate from 1 meter of tube length if there are no fins.