Carbon is not a well defined material. Its structure and electronic
properties are sensitive functions of the heat treatment temperatures.
Therefore "alpha" will vary with heat treatment temperature.
Larry Woolf; General Atomics; 3550 General Atomics Court, San Diego, CA
92121; Phone:858-455-4475; FAX:858-455-4268; http://www.sci-ed-ga.org
-----Original Message-----
From: Ludwik Kowalski
Sent: Thursday, March 21, 2002 6:11 AM
Subject: Re: Flat conductors
Although the temperatures were not measured the estimated
delta(T) was about 80-25=55 C. At the room temperature
R was 2.62 kohms and it became 2 kohms at 80 C (see below).
Thus, the coefficient alpha must be close -0.004, most likely
between -0.003 and -0.005. The textbook value for carbon
is -0.0005. The difference (factor of ~8) is significant. How
can this be interpreted?