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3B SCIENTIFIC® PHYSICS
U15405 Linear thermal expansion apparatus
Instruction sheet
3/03 ALF
1
2
The apparatus demonstrates the linear expansion of
solid materials and allows the determination of expan-
sion coefficients for copper, iron and glass.
1. Safety instructions
• Caution. The experimental procedure results in hot
steam.
• Do not touch heated rods with your fingers. Use
cloths when replacing rods.
• Do not subject the glass rod to mechanical stresses.
2. Description, technical data
The equipment consists of a base track with a spring
clip at the left-hand end for attaching a testing rod. At
a distance of 50 cm from the end there is a notch in
the base strip for the pointer. The copper and iron test
rods have a ring nut 65 cm from the end for placing on
the pointer. The glass rod has a metal ring with a ring
nut in the same place. Behind the pointer is a 0-5 cm
scale. To feed in hot steam, a 10 cm long glass rod
attached to a hose is provided.
Dimensions:
Weight:
Length of rods:
Diameter of rod:
Length of pointer:
Scale markings:
Scale factor:
6
5
4
3
530 mm x 60 mm x 240 mm
0.6 kg
630 mm approx.
8 mm approx.
200 mm
mm
1 : 50
1
Spring clip
2
Base track
3
Glass rod
4
Test rods
5
Pointer
6
Scale
3. Principle
To determine the linear expansion coefficient α for vari-
ous materials, it is necessary to measure the expansion
for a certain temperature rise ∆ T. Thus the rods are
heated to 100° C by means of steam and the tempera-
ture difference ∆ T from room temperature is calculated.
The expansion is determined from the movement of
the pointer d, where a pointer movement of 50 mm
indicates an expansion of 1mm. The expansion coeffi-
cient is determined from the extension w (scale factor
1:50) and the length of rod l between the two fixed
points by means of the formula:
α =
4. Instructions for use
Also required for heating the rods is a vapor generator
or a bunsen burner heating an Erlenmeyer flask
• Attach the end of the rod without the nut to a rub-
ber hose and secure in the spring clip.
• Place the pointer in the notch under the scale and
attach the upper end of the pointer to the rod with
the ring nut.
• Adjust the pointer to zero by sliding the rod.
• Attach to a steam generator or an Erlenmeyer flask
half-filled with water by means of the short glass
rod and a hose.
• Boil water. Steam flows through the test rod and
heats it to approximately 100° C.
3
d
⋅ ⋅
T ∆
l w
®
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