3B Scientific Yi Bell User Manual

3B SCIENTIFIC® PHYSICS

U30002 Yi bell

Operating instructions

1/03 ALF

®

The Yi bell is used to demonstrate the relationship be­tween temperature and oscillation damping.

1. Safety instructions

• Only use solid fuel (Esbit) in the students’ experi­ment.

• In the demonstration experiment, do not saturate
the cloth with liquid fuel (methylated spirit).

• Exercise particular caution when igniting the fuel.

• Only ignite the fuel with matches.

• Do not touch the bell or burner during or after the

heating phase.

• Allow the bell to cool after completing the demon­stration.

2. Description, technical data

This „bell of faith“ was copied from a 2-tone bell dis­covered in 1978 in the grave of the Chinese marquis Yi
from the 5th century BC. It is cast from a newly devel­oped copper-magnesium alloy and possesses a singu­lar physical characteristic resulting from its special
shape and the effect of temperature on oscillation
damping. A curve of the energy decrement per period
is plotted against the temperature in Figure 1. The
change in the elastic characteristics of the alloy, (An2 ­A

2)/An2, expressed here as a percentage, is consider-

n+l

able from room temperature to approximately 100°C.
At room temperature, the bell only sounds dull and
wooden. However, if it is heated for several minutes
with an alcohol burner, it produces a beautiful tone.
Figure 2 shows the acoustic oscillations before and af­ter the bell is heated.
The bell is stowed in a robust wooden box with a fabric
and velvet lining.

Energy decrement per period %

Temperature in °C

Figure 1

Graph of energy decrement per period as a function of temperature

Figure 2

Change in the attenuation and frequency of the bell before and after
heating. Top: cold; bottom: hot

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Dimensions: 295 mm x 210 mm x 120 mm
Weight: 3000 g
Storage box: 330 mm x 265 mm x 145 mm

3. Scope of delivery

Bell
Bronze base plate with wooden support beams
Bronze suspension device
Alcohol burner with cover
Wooden hammer
Storage box

4. Procedure

• Moisten the loth with liquid fuel (methylated spirit)
from the burner. In the students’ experiment, only
use solid fuel.

• Position the burner below the bell.

• Ignite the fuel carefully with a long matchstick.

• Heat the bell for 2-3 minutes.

• Place the cover carefully on the burner to extin-

guish the flame.

• Strike the bell with the hammer.

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

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