3B Scientific Thermal Expansion Apparatus S User Manual

3B SCIENTIFIC® PHYSICS

U15405 Linear thermal expansion apparatus

Instruction sheet

3/03 ALF

®

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The apparatus demonstrates the linear expansion of
solid materials and allows the determination of expan­sion 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 r od 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: 530 mm x 60 mm x 240 mm
Weight: 0.6 kg
Length of rods: 630 mm approx.
Diameter of rod: 8 mm approx.
Length of pointer: 200 mm
Scale markings: mm
Scale factor: 1 : 50

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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 vari­ous 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 tempera­ture difference ∆T from room temperatur e 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 coeffi­cient 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:

=

⋅⋅

lw T

d

∆

Also required for heating the rods is a vapor g enerator
or a bunsen burner heating an Erlenmeyer flask

• Attach the end of the rod without the nut to a rub­ber 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.

α

4. Instructions for use

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(Note: at high altitudes, water boils at slightly less
than 100° C.)

• When steam has been passing through the rod for
about 1 minute and no more condensing steam is
emerging from the end of the rod, read off the larg­est movement of the pointer.

Temperature rise ∆T= 78° C
Pointer movement for copper rod d = 32.5 mm
Extension w = 50
Length of rod l = 500 mm

32 5

α

=

.

500 50 78

⋅⋅

= 16,7 · 10–6 /° C

5. Example calculation

Room temperature T1 = 22°C
Temperature of steam = 100° C

Table of values:

Copper: 16.8 · 10-6 /° C
Iron: 12 · 10-6 /° C
Glass: 9 · 10-6 /° C

3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • www.3bscientific.com • Technical amendments are possible

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