Lab 4 Expansion of a Solid with increasing Temperature
Physics 2B – Jordan and Cascarano
Goal: To determine the coefficient of linear expansion of various metals to
confirm the values generally accepted and to determine whether different
metals expand at different rates.
Equipment: water boiler, Bunsen burner, stand, tubing, rods of different
metals, Cenco apparatus designed to heat the rod along its length with steam,
a thermometer to measure the temperature, an electric contact screw with a
graduated scale to measure the change in length due to the rise in
temperature, an ohm meter.
Procedure:
1. Assemble the instrument by inserting a rod of a particular metal into the
rubber stoppers of the cylindrical steel jacket and connect the tubing
from the boiler to one end of the jacket around the rod.
2. Put water in the boiler and tubing from the other end of the jacket to a
condensation beaker. Install the thermometer and stopper in the jacket
top.
3. Adjust the measurement screw until it is just touching the rod. Use the
ohm meter to determine when the screw is just touching the rod. Read
the scale and vernier behind the screw. Determine the units of the
scale.
4. Back out the screw, turn on the burner and wait until the steam reads
100o C and you think the rod temperature is in equilibrium with the
steam. Adjust the measuring screw again until it just makes contact.
Read the scale.
5. Find the difference in mm. between before and after.
6. Repeat for 3 other metals.
7. Compare with the accepted values and with each other.
Data Analysis:
Compute the coefficient of linear expansion  from the formula
L = Lo T
Lo is the length of the rod at room temperature.
Error analysis: Determine all possible sources of error and estimate their size
(accuracy in temperature, length, purity of material, establishment of the
equilibrium temperature of rod, etc). Comment on which will have the
greatest impact on your result.
Present your values of with errors and conclude whether your numbers agree
with the acceptable numbers (see text)