3B Scientific Test Vessel User Manual

3B SCIENTIFIC® PHYSICS

Ultrasonic CW generator U10006

Laser diode for Debye-Sears effect U10007

Test vessel U10008

Instruction sheet

8/03 ALF

®

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Ultrasound generator with accessories for the Debye­Sears experiment and for demonstrating standing ul­trasonic waves.

Safety instructions

Before switching on the ultrasound generator and ac­cessories, carefully read the following instructions for
the sake of your safety and for the safety of the equip­ment.

• The slits in the device are for ventilation and must

be kept clear to avoid overheating the equipment.
It is recommended that the device be placed on its
own stand (also included).

• Before switching on the device make sure that it is

adjusted to the mains voltage you intend to use.
Make sure that you keep within the operating speci­fications.

• Never try to push objects through the slits in the

device since this could cause short circuits or elec­tric shocks.

• Only use 3B’s own ultrasound transducer with the

“PROBE” connection. Be careful, voltages may be
as high as 70 V.

• Do not use the ultrasound transducer for a lengthy

period without contact to fluids. Otherwise the
transducer may overheat and be destroyed.

• Do not turn on the U10007 laser diode if there are

1 Laser diode

2 Test vessel

3 Ultrasonic transducer

people standing in the beam. This is a class II laser
with power < 1 mW. Do not look into the beam or
aim it at other people or animals.

• Beware: high-powered ultrasound! Do not use the

probe on people or animals.

Contents

1. Introduction ............................................ 7

2. Components ............................................ 7

2.1 Ultrasound generator - operating elements 7

2.2 Set-up for test container 8

2.3 Lens on glass slide 8

2.4 Laser diode (U10008) 8

3. Experiment procedure .............................. 8

3.1 General instructions for experiments 8

3.2 Debye-Sears effect 9

3.3 Projection of standing ultrasonic waves 9

4. Technical details ..................................... 10

1.1. Ultrasound generator 10

4.2. Ultrasonic transducer 10

4.3. Test vessel 10

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1. Introduction

In 1932 Debye and Sears demonstrated for the first time
how light is refracted when passing through a fluid ex­cited to high-frequency oscillation. The maxima and
minima in density act here like the grid elements of
an optical diffraction grating. The grating constant
corresponds to the ultrasonic wavelength and is thus
dependent on the frequency of the ultrasound and the
speed of sound in the medium through which the
sound is travelling.
The CW (continuous wave) generator with its accompa­nying broad-band ultrasound transducer, along with
an adjustable test vesseland its integrated laser holder,
mean that it is possible for the first time to demon­strate this phenomenon to schoolchildren and college
students alike using simple and compact equipment.
The equipment can demonstrate both frequency de­pendence (with four different frequencies) and the ul­trasonic wavelength in various fluids, allowing the
speed of sound in the medium to be calculated.
It is also possible to project standing ultrasonic waves
by inserting an optical lens between the laser source
and the ultrasonic waves. The waves are then projected
by the diverging laser beam.

2. Components

2.1 Ultrasound generator - operating elements

The ultrasound generator generates continuous high­power ultrasonic waves (CW = continuous wave). The
voltage bmcan be adjusted between 5 and 65 V. There
is an LCD display for the voltage output bl. The trans­mitted voltage can be switched off separately 8. The
frequency can be set to one of four frequencies (1, 2, 4
or 8 MHz) 9. An additional monitor output 7 allows
the output frequency to be determined precisely with
the aid of an oscilloscope or a frequency counter. A
suitable output 3is provided to supply power to a
laser diode. This can also be switched off separately

2.

Adjustment of mains voltage

The ultrasound generator can operate with 230 V or
115 V mains voltage. A voltage selector switch is situ­ated on the rear of the casing and is hidden beneath
the covering to the right of the rear panel. A screw­driver is used to alter the switch setting (see illustra­tion). If the mains voltage is altered, the fuse needs to
be changed to suit the mains voltage. A T630 mA fuse
should be used with 115 V mains voltage and a T315
mA fuse for 230 V mains.

Warning:

Unplug from the mains before altering the mains set­ting.
No voltage may be applied to the device while making
the adjustment,

1 2 3 4 5 6 7

1 Mains switch
2 On/off switch for laser
3 Connector socket for laser
4 Control light for laser
5 Connector socket for ultrasonic transducer
6 Control light for ultrasonic transducer
7 Monitor output
8 On/off switch for ultrasound
9 Frequency selection switch
bl Voltage display
bm Voltage setting

bm

bl

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115

230

1 Remove the two screws from the rear panelling and take off

the panel. The voltage selector switch is revealed.

2 Fuse

115 V 630 mA
230 V 315 mA

3 An arrow indicates the voltage that is currently set. Adjust using

a screwdriver inserted into the slit.

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