Midterm2_ENGR 220

Midterm2_ENGR 220 - tDEC-211 MIDTERM #2 NAME (Print)_...

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Page Total:  1 tDEC-211 MIDTERM #2 NAME (Print)__________________ Section ____ Fall 2005 ( M. W. Barsoum) Note: Closed book, closed notes exam. Formula sheet is given at the end. Note: You may use a calculator and ruler. You will have one hour to complete the exam. Note: Please show all work and correct units for full credit. 1. For the following questions choose the correct answer and fill in the blanks, if needed. i) pts 7 The concentration of vacancies in a solid increases/decreases/stays the same (choose one) with increasing temperature. If the energy needed to form a vacancy is 3eV, the ratio of the number of vacancies to number of atomic sites at 1000 K would be: Note: writing the correct equation with correct dimensions and units, etc. will get you most of the pts. Ans. = 7.8 x 10 -16 ii) pts 3 The following 3 defects can be found in solids: _______________________________ iii) pts 4 The resistance of a wire of length L is the same/higher than/less than (choose one) one that is 2L long. The same can/cannot (choose one) be said of the resistivity because _____________________ _ v) pts 4 The electrical conductivity of metals is low/high (choose one) relative to that of semiconductors
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Midterm2_ENGR 220 - tDEC-211 MIDTERM #2 NAME (Print)_...

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