PASCO TD-8558A THERMAL EXPANSION APPARATUS - Manual (Page 11)

012-04394C Thermal Expansion Apparatus
1
Teacher’s Guide
Experiment: Measuring the Coefficient of Linear Expansion for Copper, Steel and Aluminum
Notes on Procedure
➉ If you allow too much time to elapse before making
your length measurement, the guage rod will absorb
heat, which will decrease the measurement. The
thermistor takes longer to reach equilibrium than
the tube, though; so you must allow a fair amount
of time for your temperature measurement to stabi-
lize. To get the best results despite these problems,
record the maximum change in length recorded by
the guage and the minimum resistance recorded by
the ohmmeter.
Data and Calculations
DATA CALCULATIONS
L (mm) Rrm (
Ω
)
∆
L (mm) Rhot (
Ω
) Trm (C
°
) Thot (C
°
)
∆
T (C
°
)
Copper 700 99,100 0.88 5,910 25.1 98.0 72.9
Steel 700 99,300 0.61 5,970 25.1 97.9 72.8
Aluminum 700 102,000 1.19 5,880 24.5 98.5 74.0
α
Cu
= 17.25 x 10 -6 /C
°
α
steel
= 11.97 x 10 -6 /C
°
α
Al
= 23.1 x 10 -6 /C
°
Notes on Questions
➀ The values for Copper and Aluminum are within
2% of the accepted values, and are both low. The
value for steel was within the accepted range. (Steel
has a wide range of linear expansion coefficients,
due to varying composition.)
➁ Answers will vary
➂ α
vol
≈
(
α
linear
)
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TABLE 1 Data and Calculations