# Homework Help: How to make Resisitivity vs. Temperature graph from in-lab measurements

1. Oct 16, 2012

### JosephK

We used a wheatstone bridge, which is an electric circuit consisting of four resistors.Two of the resistors are known, one resistor is a large "resistor" with dials that control the resistance, and the fourth resistor can either be a metal or semiconductor. The metal was heated to about 290 °C.

As the metal cooled, I moved a metal slider across a metal line so that the ammeter read zero and we recorded the position of the slider every 5 degrees or so.

A sample of the data is:

Temperature (°C) Ratio (cm)
190 89.7
185 87.7
180 87.2
175 85.9
170 84.6
165 83.5
160 81.6
155 80
150 77.9

This is for a semi conductor. When I looked in a Intro to Physics book, I saw a rho (resistivity) verses temperature graph for a semiconductor. Now I wonder if I have all the data needed to make my own. If not, what can I do in this lab to obtain the necessary data?

Also, I need to understand what "Fermi-energy" is. What are phonons? What is bandstructure, energy levels of electrons in solids, fermi distribution, densisty of states?

I know what scattering of electrons is. The intro to physics book says that, when a metal is hot, the ions vibrate back and forth faster, and it is difficult for an electron to go through without getting pushed back.