# Questions 2.1

Questions to Chapter 2.1.1

| Here are some raw questions
| 1. Give examples and orders of magnitude for carrierr concentrations in various materials including the temperature dependence
|  | Metals: k = 1....3 electrons per atom, n = k · density of atoms = k · (specific weight / atomic weight). Examples for n = 1,2,3,.... (????) n(T) independent of T; exception (semimetals, ...) electrolytes (????) graphite, ??? semicnductors Superconductors
| s and crystal lattice defects. What kind of defects would influence s? Most effecient defects?
|  | Point defects, dislocations, grain boundaries, precipitations, second phases, ... Point defects; l -argument.
| T-dependence or Al resitance. Give graph. Compare to rule of thumb Resistivity of Al lines on ME circuits limits maximum length to l = 1 mm because R·C has to be kept below a certain value. Assuming that R and C are proportional to l; would it make (commercial) sense to replace the Al by a superconductor if length of 5 mm are required? Note: If a superconductor is used, the device needs to be cooled to < 100 K.
|  | If theAl resistance decrease about 5 fold, it makes no sense
| Figure of merit: High voltage cable, must withstand load of ... Own weight also important,..., price, resistivity,...
|  | ????
| Multiple choice questions
|  | Chapter 2.1.1 Metals
|  | Ohms law Matthiesen rule r(T) rule Some numbers / order of magnitude for s
|  | Chapter 2.1.2 Alloys
|  | Immiscibility: Resitivity alloys < or > then constituents? Nordheim rule Graph for partial micibiliy gap: What happens for coplete immiscibility? for smalle range of ...? Resisitivity intermetallic comiound, Why large than elements? (List of answers)
|  | Chapter 2.1.3 Non-metallicCondctors
| In addition: MC Questions from "Fischer" p. 155
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2.3.1 Special Applications

Solution to 2.3.1