Lab 9: Thermal Expansion
Description
In this lab, by measuring the length change,∆Lof a metal rod as its temperature is changed,
you will determine the coefficient of thermal expansion α.
Extra Safety Precautions
In this lab we will be using boiling water and steam, both of which present a hazard that people
tend to underestimate. The water is boiling on the tables at which you are sitting.This means
that boiling water could easily end up in your lap if you fail to adhere to these safety
precautions! Note that there is also boiling water at the table immediately behind you!
Precautions:
•BE AWARE OF YOUR MOVEMENTS. Do not bump your own table or push your chair
into the table behind.
•DO NOT SIT WITH YOUR LEGS UNDER THE TABLE when hot or boiling is sitting on
your table. If the water spills while you are sitting under the table, it will burn your lap.
•BE VERY, VERY CAREFUL. Do not underestimate the hazards of multiple pots of boiling
water in a busy room.
Also, please be careful with the steam generator. Steam burns can be nasty. In particular, be
careful to keep your face away from the openings in the steam generator. Stoppers and caps should
always be loosely inserted to prevent the possibility of a buildup of pressure and a subsequent steam
explosion or release of a high-pressure jet of steam and/or hot water. If stoppers with small holes
are available, they are likely to be safer and equally effective.
Equipment
•Linear Expansion Apparatus
•Steam Boiler with 2 stoppers (one with a hole, one without)
•Hot Plate
•Thermometer
•1 Brass (or copper) rob and 1 aluminum rod
•Power Supply
Introduction
Most materials expand in proportion to the temperature change. The fractional expansion (or
contraction) ∆L
L0of the material along one axis is proportional to the change in the temperature
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