ENGRI111_HW2_2004 - a) Which cell has to be on top (first...

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ENGRI 111 Homework #2 Due Friday, September 17 1. Explain a) why silver appears silvery while b) gold appears golden. c) What color(s) of light would you expect to see when looking through a thin piece of gold? 2. Comment on the transparency (or lack thereof) in the infrared region for a) alumina, b) silver, and c) silicon. 3. Solar cell A uses a semiconductor with a band gap of 1 eV. Solar cell B uses a semiconductor with a band gap of 2 eV. Either cell is thick enough to absorb all the light above its band gap. Both cells can work simultaneously with one on the top of the other to operate more efficiently in a small space.
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Unformatted text preview: a) Which cell has to be on top (first to receive the sunlight) for both to work simultaneously, and b) why? 4. Explain why the partially filled band in sodium metal is exactly half filled. 5. A solid has a completely filled lower energy band and a partially filled higher energy band. a) Predict the electrical properties of this solid on the basis of its band diagram. b) What would happen to the electrical properties of this solid if all of the electrons were removed from the conduction band and why? c) In chemical language is this an oxidation or a reduction process?...
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