Physics
Lab 2.9
Overview
The purpose of this laboratory class is to measure the
coefficient of thermal expansion of a metal by heating a
metal pipe with steam and measuring the increase in
length.
Experiment
2.9.1 Coefficient of Linear Expansion
Equipment
Water boiler (Steam generator)
Vernier calipers
Protractor
Hose – neoprene
Metal pipe about 2 meters long (copper, steel, aluminum)
Thermometer
Clamping device
Wooden skewer or thin dowel with pointer attached.
Procedure:
- Clamp one end of the
metal pipe to the top of a sturdy table.
- Connect a hose from a
steam generator to the clamped end of the pipe.
- Ensure that the steam
generator is in a stable position – If
necessary, support the hose in such a way that it
does not affect the stability of the water boiler.
- Rest the other end of
the pipe on the pointer so that the pointer will
move when the pipe expands.
- Measure the distance
from the clamp to the point where the pipe is
resting on the pointing device.
- Place a piece of
cardboard behind the pointer and record the
position of the pointer while the pipe is at room
temperature.
- Measure the room
temperature.
- Attach a thermometer
to the pipe and wrap some cloth or insulating
material around the thermometer and pipe. Ensure
that the thermometer bulb is touching the pipe.
- Allow steam to
condense on the inside of the pipe and monitor
the temperature of the outside of the pipe.
- The pointer will move
as the pipe expands. When the pointer stops
moving, mark the position of the pointer and
measure the temperature of the outside surface of
the pipe.
- Using a protractor,
measure the angle through which the pointer has
moved.
- Using the calipers,
measure the diameter of the part of the pointing
device that the pipe was resting on.
Results –
Experiment 2.9.1
Coefficient of linear
expansion
| Metal used |
|
| Diameter of pointing device |
|
| Initial temperature of pipe (room
temp) |
|
| Initial length of pipe (from
clamp to pointer) |
|
| Temperature of pipe - Final |
|
| Temperature increase (Final
– room temp) |
|
| Angle moved by pointer |
|
| Length increase – pipe |
|
| Coefficient of linear expansion = |
|
Calculations
Calculate the
coefficient of linear expansion as follows:
. . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . .D L
The coefficient of linear expansion: a = ----------
.
. . . . . . . . . . . . . . . . . . . . . . . . . . . L0 D T
D L = length increase by pipe
L0
= initial length of pipe
D T = increase in temperature
|
