PASCO TD-8561 THERMAL CONDUCTIVITY APPARATUS - Manual (Page 9)

012-03349D Thermal Conductivity Apparatus
5
Teacher’s Guide
Experiment: Thermal Conductivity Apparatus
Notes on Procedure
➀ Expect 10-15% error under normal (student labora-
tory) operating conditions.
➁ Keep the ice as isolated from the surroundings as
possible. Our best results were obtained using a
PASCO styrofoam calorimeter cup as an ice mold;
however, this has the disadvantage of splitting the
cup when the water freezes. (Medium-sized
styrofoam cups also work very nicely.) Whatever
mold you use, leave it on the ice during the experi-
ment.
➂ Apply a dab of grease to the joint between the plate
and the water trough to prevent leakage. Vaseline ®
works well; it melts, but still seals the gap.
A note about the aluminum covers on some
samples: This was found experimentally to have no
measurable effect on the conductivity of the
samples. We tested this using a glass plate which
we measured both with and without an aluminum
cover, and there was no statistically significant dif-
ference between multiple readings in both states.
Accepted Values
Substance cal•cm/cm 2 •sec•
°
C watt•m/m 2 •K
Masonite 1.13 x 10- 4 0.047
Wood (Pine) 206 - 3.3 x 10- 4 0.11 - 0.14
Lexan 4.6 x 10- 4 0.19
Sheet Rock 10.3 x 10- 4 0.43
Glass 17.2 - 20.6 x 10- 4 0.72 - 0.86
Note
Values (with the exception of Lexan) from the Handbook of Chemistry and Physics, 46th Edition, published by
The Chemical Rubber Company. Value for Lexan is from a specifications sheet provided by the manufacturer.
Values for Masonite and for Sheet Rock will vary considerably.
➃