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6. Wave excitation
Water depth, depth of immersion of the wave
exciters as well as frequency and amplitude of
the vibrator must be carefully selected in order
to present the optimum representation of the
phenomena to be observed.
When the vibrator and stroboscope frequencies
are synchronised, it is possible set up a view of
standing waves.
If the frequency is altered, it may require a read-
justment of the amplitude in certain cases.
In some experiments, e.g. diffraction and reflec-
tion, it may be necessary to set certain ranges of
the wave pattern to an enhanced resolution.
This is done by modifying the amplitude accord-
ingly.
6.1 Excitation of straight wave fronts
•
Insert the extension tube into its slot on mo-
dule 1, tighten the knurled screws and fas-
ten it into the holder.
•
Set the depth of the exciter module by ad-
justing the height of the holder such that the
lower edge of the module is just touching the
surface of the water.
•
On the control unit, set the desired fre-
quency and amplitude.
On the viewing screen, a stationary or slowly
moving wave pattern can be observed.
•
Make fine adjustments using the rotary
knob.
6.2 Excitation of circular waves
•
Attach exciter module 3, for generating cir-
cular waves, to the holder.
•
Set the depth of the exciter module by ad-
justing the height of the holder such that the
lower edge of the module is just touching the
surface of the water.
•
On the control unit, set the desired fre-
quency and amplitude.
On the viewing screen, a stationary or slowly
moving wave pattern can be observed.
•
Make fine adjustments using the rotary
knob.
6.3 Excitation of interfering circular waves
•
Attach exciter module 2, for generating inter-
fering circular waves, to the holder.
•
Set the depth of the exciter module by ad-
justing the height of the holder such that the
lower edge of the module is just touching the
surface of the water.
3B Scientific GmbH ▪ Rudorffweg 8 ▪ 21031 Hamburg ▪ Germany ▪ www.3bscientific.com
•
A standing wave image, or one that drifts only
slightly, featuring two circular waves can be
seen on the screen. The waves interfere with
each other where they overlap.
•
6.4 Determining the wavelength
When determining the wavelength, the magnifi-
cation factor b must be taken into account.
Magnification factor b can be calculated by plac-
ing the biconcave lens onto the ripple tank for
instance and checking the ratio of its actual size
A to the size of its projection on the viewing
screen A'.
b = A'/A
The actual wavelength λ can be calculated from
the wavelength λ' measured on the viewing
screen as follows.
λ = λ'/b
•
•
Subject to technical amendments
© Copyright 2014 3B Scientific GmbH
On the control unit, set the desired fre-
quency and amplitude.
Make fine adjustments using the rotary
knob.
7. Storage and maintenance
Store the ripple tank in a dust-free place.
Thoroughly dry the ripple tank after use to
prevent it developing water stains and lime
scale deposits.
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