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Instruction Sheet
for the PASCO
Model WA-9771
012-05722A
5/95
$1.00
better
teach science
ways to
Phone (916) 786-3800 FAX (916) 786-8905 email: [email protected]
10101 Foothills Blvd. P.O. Box 619011 Roseville, CA 95678-9011 USA
PROJECTION SCREEN ACCESSORY KIT
Introduction
The PASCO Model WA-9771 Projection Screen Acces-
sory is designed to be used with the PASCO WA-9775
Ripple Tank System to display wave patterns in large
classrooms and lecture halls. The accessory includes an
acrylic mirror, a white translucent screen and four pre-cutVelcro strips.
Equipment
The PASCO Model WA-9771 Projection Screen
Accessory includes the following:
acrylic mirror (approximately 53 X 40cm)
acrylic screen (approximately 48 X 37cm)
four Velcro loop strips
(approximately 8.5 X 5cm)
Setup Procedure
Assemble the WA-9773 Ripple Tank as per the in-
structions in the Ripple Tank manual.
Turn the Ripple Tank so the front is facing you (label
side toward you).
Peel the protective backing from a Velcro loop strip
and affix it to the top of the right front leg by placing
the center of the strip on the front of the leg and wrap-
ping the ends toward the back of the leg as shown in
Figure 1. Affix a second strip to the bottom of the
right front leg. Repeat this procedure for the left frontleg.
Peel the protective plastic film from the mirror and
screen.
Install the mirror by sliding the mirror flange into the
back of the Ripple Tank between the frame and the
glass. See Figure 2.
Connect the viewing screen to the Ripple Tank by
aligning the Velcro hook on the screen with the
Velcro loop on the legs and pressing firmly together.
1995 PASCO scientific
This instruction sheet written/edited by:
Mary Ellen Niedzielski
Velcro is a registered trademark
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2
Projection Screen Accessory Kit 012-05722A
Limited Warranty
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workman-
ship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return ship-
ment will not be covered by the warranty.) Shippingcosts for returning the equipment, after repair, will be
paid by PASCO scientific.
Equipment Return
Should this product have to be returned to PASCO scien-
tific, for whatever reason, notify PASCO scientific by
letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping instruc-
tions will be promptly issued.
NOTE:
NO EQUIPMENT WILL BE ACCEPTED FOR
RETURN WITHOUT AN AUTHORIZATION.
When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the fol-
lowing rules:
The carton must be strong enough for the item
shipped.
Make certain there is at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.
Make certain that the packing material can not shift in
the box, or become compressed, thus letting the instru-
ment come in contact with the edge of the box.
WA-97
73
RIPPLE
TANK
FRAGILE
- GLASS
DRAINT
ANKAFT
ERUSE
acrylicmirror
Velcrostrip (4)
acrylic
screen
WA-9773Ripple Tank
Figure 1: Projection Screen Accessory Assembly
acrylic mirror
glass andgasket ofripple tank
ripple tank leg
Figure 2: Location of Mirror Flange
ripple tankframe
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Instruction Sheet
for the PASCO
Model WA-9773
012-05837A
5/95
$1.00
better
teach science
ways to
Phone (916) 786-3800 FAX (916) 786-8905 email: [email protected]
10101 Foothills Blvd. P.O. Box 619011 Roseville, CA 95678-9011 USA
RIPPLE TANK
long straightreflector (2)
mini straightreflector
curvedreflector
triangularrefractor
convexrefractor
concaverefractor
clear plasticrule
rubberstopper
tank frame
tank legs (4)
short straightreflector
Introduction
The WA-9773 Ripple Tank is the core of the Basic
Ripple Tank System and allows the user to create wave
patterns. The neoprene rubber walls damp the waves that
would reflect and disturb the primary wave and interfer-
ence patterns. The tempered glass bottom ensures a uni-
form water depth for all ripple tank experiments. A smallhole in the glass bottom and a standard rubber stopper
make draining the tank easy. The tank legs are removable
and can be stored in the tank itself so multiple tanks can
be stacked on top of one another. Each tank is shipped in
protective reusable packing for easy storage.
WA-9773 Ripple Tank specifications:
width 47.5cm X 47.5cm (19 X 19)
height 45cm minimum (feet of tank legs are
adjustable)
viewing area 39.5cm X 39.5cm (16 X 16)
water capacity 1.2-2.0 liters (1.1-1.8 quarts) or 6-
8mm (.25-.32), 8-10mm (.32-
.40) deep for refraction experiments
Equipment
The WA-9773 Ripple Tank includes the following:
glass tank with rubber gasket
steel tank frame
tank legs (4) with adjustable feet
triangular refractor
convex refractor
concave refractor
curved reflector
mini straight reflector
short straight reflector
long straight reflector (2)
rubber stopper
clear plastic cm/inch rule
1995 PASCO scientific
This instruction sheet written/edited by:
Mary Ellen Niedzielski
tank with rubber wallsand glass bottom
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2
Ripple Tank 012-05837A
Assembly
To assemble the tank, screw a leg into the bottom of each
of the four corners of the tank frame. Place the glass plate
into the top of the tank frame so the rubber sides form a
basin for the water. If the glass plate does not touch the
tank frame at all four corners, use the leveling feet to re-shape the frame to fit the glass plate. Insert the rubber
stopper into the drain hole in the glass plate and push
down on it to make sure the water will not leak out. See
Figure 1.
When filling the tank with water, the water level must be
above the step on the rubber boundary so reflections will
be minimized. Most experiments require from 1.2 liters to
2.0 liters of water. The tank can be leveled by checking
the depth of the water in three of the four corners.
Cleanup and Storage
To empty the tank, place a container under the drain hole
and remove the rubber stopper. When the water stops
flowing out of the hole, raise the corner of the tank oppo-
site the hole so the rest of the water will drain out. Use a
towel to dry the glass tank. Replace the rubber stopper for
storage. Store the glass tank in its custom shipping box.
ripple tank leg (4)
steel tank
frame
Figure 1: Ripple Tank Assembly
Limited Warranty
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of oneyear from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workman-
ship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return ship-ment will not be covered by the warranty.) Shipping costs
for returning the equipment, after repair, will be paid by
PASCO scientific.
Equipment Return
Should this product have to be returned to PASCO scien-
tific, for whatever reason, notify PASCO scientific by let-
ter or phone BEFORE returning the product. Upon notifi-
cation, the return authorization and shipping instructions
will be promptly issued.
NOTE:
NO EQUIPMENT WILL BE ACCEPTED FOR
RETURN WITHOUT AN AUTHORIZATION.
When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the fol-
lowing rules:
The carton must be strong enough for the item
shipped.
Make certain there is at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.
Make certain that the packing material cannot shift in
the box, or become compressed, thus letting the instru-
ment come in contact with the edge of the box.
glass tank withrubber gasket
rubberstopper
leveling foot
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Instruction Manual andExperiment Guide forthe PASCO scientific
Model WA-9775
012-05846A
11/95
1995 PASCO scientific $10.00
BASIC RIPPLETANK SYSTEM
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i
012-05846A Basic Ripple Tank System
Table of Contents
Section PageCopyright, Warranty, and Equipment Return ................................................... ii-iii
Introduction ...................................................................................................... 1
Equipment ........................................................................................................ 2
Assembly
Assembly of the Tank ................................................................................. 4
Clean-up and Storage .................................................................................. 4
Mounting the Light Source .......................................................................... 5
Mounting the Ripple Generator ................................................................... 5
Generator Attachments ........................................................................... 6
Height Adjustment ................................................................................. 6
Frequency Adjustment ........................................................................... 6
Amplitude Adjustment ........................................................................... 7
Phase Difference .................................................................................... 7
Experiments
Exp 1 Reflection ......................................................................................... 9
Exp 2 Refraction ........................................................................................ 13
Exp 3 Diffraction ....................................................................................... 17
Exp 4 Interference ...................................................................................... 21
Exp 5 Image Formed by a Plane Mirror ...................................................... 25
Exp 6 Dependence of Wave Speed on Water Depth ................................... 27
Technical Support ...................................................................................... Back Page
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ii
Basic Ripple Tank System 012-05846A
Copyright, Warranty and Equipment Return
Copyright Notice
The PASCO scientific 012-05846A Basic Ripple Tank
System manual is copyrighted and all rights reserved.
However, permission is granted to non-profit educational
institutions for reproduction of any part of the (manual
title) manual providing the reproductions are used only
for their laboratories and are not sold for profit.
Reproduction under any other circumstances, without the
written consent of PASCO scientific, is prohibited.
Limited Warranty
PASCO scientific warrants the product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace at its option any part of the product
which is deemed to be defective in material or
workmanship. The warranty does not cover damage to
the product caused by abuse or improper use.
Determination of whether a product failure is the result of
a manufacturing defect or improper use by the
customer shall be made solely by PASCO scientific.Responsibility for the return of equipment for warranty
repair belongs to the customer. Equipment must be
properly packed to prevent damage and shipped postage
or freight prepaid. (Damage caused by improper packing
of the equipment for return shipment will not be covered
by the warranty.) Shipping costs for returning the equip-
ment after repair will be paid by PASCO scientific.
Credits
Author: Jon HanksEditor:
PleaseFeel free to duplicate this manual
subject to the copyright restrictions below.
Equipment Return
Should the product have to be returned to PASCO
scientific for any reason, notify PASCO scientific by
letter, phone, or fax BEFORE returning the product.
Upon notification, the return authorization and
shipping instructions will be promptly issued.
When returning equipment for repair, the units
must be packed properly. Carriers will not accept
responsibility for damage caused by improper
packing. To be certain the unit will not be
damaged in shipment, observe the following rules:
The packing carton must be strong enough for the
item shipped.
Make certain there are at least two inches of
packing material between any point on the
apparatus and the inside walls of the carton.
Make certain that the packing material cannot shift
in the box or become compressed, allowing the
instrument come in contact with the packing
carton.
Address: PASCO scientific
10101 Foothills Blvd.Roseville, CA 95747-7100
Phone: (916) 786-3800
FAX: (916) 786-3292
email: [email protected]
web: www.pasco.com
NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION FROM PASCO.
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1
012-05846A Basic Ripple Tank System
Introduction
The WA-9775 Basic Ripple Tank System consists of
three components which enables the user to perform ex-
periments and to demonstrate basic wave and optics
theory. Each component is described below.
The WA-9773 Ripple Tank is the core of the Basic
Ripple Tank System and allows the user to create wave
patterns. The neoprene rubber walls damp the waves that
would reflect and disturb the primary wave and interfer-
ence patterns. The tempered glass bottom ensures a uni-
form water depth for all ripple tank experiments. A small
hole in the glass bottom and a standard rubber stopper
make draining the tank easy. The tank legs are removable
and can be stored in the tank itself so multiple tanks can
be stacked on top of one another. Each tank is shipped inprotective reusable packing for easy storage.
WA-9773 Ripple Tank specifications:
width: 47.5cm X 47.5cm (19 X 19)
height: 45cm minimum (feet of tank legs are
adjustable)
viewing area: 39.5cm X 39.5cm (16 X 16)
water capacity: 1.2-2.0 liters (1.1-1.8 quarts) or 6-
8mm (.25-.32), 8-10mm (.32-
.40) deep for refraction experimentsThe WA-9776 50W Halogen Point Light Source provides
a bright, nearly perfect point source for sharp wave pat-
tern projection. The point source is created by placing the
halogen light so the filament sits perpendicular to the
tank. The filaments position means the tip of the fila-
ment, rather than the length, faces the surface of the wa-
ter. The light source includes a built-in rod clamp.
WA-9776 50W Point Light Source specifications:
bulb type: 50W, 12 volt, type T-4 halogen
power requirements: 100-240 VAC
The WA-9777 Basic Ripple Generator can produce true
sinusoidal motion when the universal dippers (rubber
actuators) are used. Plane wave and multiple point wave
sources can also be produced with the included plane
wave actuator bar. A DC motor driving a pair of cams
provide the wave motion, with a phase adjustment of 0-
360, on two separate points. The WA-9777 uses a
phase lock knob to prevent the phase from changing un-
expectedly while in use. The three adjustment screws ac-
curately position the plane wave actuator bar or one or
two rubber actuators on the surface of the water. The
mount is mechanically isolated from the ripple tank
which ensures sharp wave patterns. The mechanical
ripple generator includes a built-in rod clamp.
NOTE:Loosen the phase lock knob to adjust the
phase and tighten to lock the phase in. Tighten just
enough to prevent the phase from changing due to
the vibration of the ripple arms. Over tightening
may cause a decrease in frequency.
WA-9777 Basic Ripple Generator specifications:
frequency: 2-20Hz
amplitude: 0.5-2mm (.02-.08) peak-
to-peak
dipper diameters: 0.6 (.25), 2.0 (.79), and
3.2 cm (1.25) diameters
plane wave attachment: 30cm (12) long
power supply: 9 VDC adapter (included)
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2
Basic Ripple Tank System 012-05846A
Equipment
rubberstopper
tank legs (4)
tank frame
mini straightreflector
short straightreflector
long straightreflector (2)
convex refractor
clear plasticrule
concave refractor
triangularrefractor
curvedreflector
WA-9773 Ripple Tank Equipment
tank with rubber wallsand glass bottom
The WA-9773 Ripple Tank includes the following:
glass tank with rubber gasket steel tank frame
tank legs (4) with adjustable feet
triangular refractor
convex refractor
concave refractor
curved reflector mini straight reflector
short straight reflector
long straight reflector (2)
rubber stopper
clear plastic cm/inch rule
WA-9776 50W Halogen Point Light
Source Equipment
WA-97
76
50WHAL
OGEN
POINT
LIGHT
SOURCE
light sourceassembly with rod
clamp
The WA-9776 50W Halogen Point Light Source
includes the following:
light source assembly with rod clamp
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3
012-05846A Basic Ripple Tank System
FREQUENCY
AMPLITUDEADJUST
A
MIN
MAX
7
6
5
4
3
2
1
G
BC
D
E
F
HI
J
PHASE360
270
180
900
WA-9777 Ripple Generator Equipment
plane wave actuatorbar assembly
small rubberactuators (3)
actuatorforearms (2)
mechanical ripplegenerator assembly
large rubberactuators (3)
FREQUENCYAMPLITUDE ADJUST
A
MINMAX
7 6 5 4 3 2 1
G
B C
D
E
F
HI
J
PHASE
360
270
18090
0
CAUTION!
LOOSEN
PHASE
LOCK
KNOB
ON
OPPOSITE
SIDE
BEFORE
ADJUSTING
PHASE
9 VDC500mAAMPLITUDE ADJUST
MAXMIN
1 2 3 4 5 6 7
WA-9777 BASICRIPPLE GENERATOR
GND
+9VDC3.5mmLOOSEN TO
ADJUST
TIGHTEN TO
LOCK
PHASE LOCK KNOB
power input jack
rod clamp
amplitude adjustment(1mm - 4mm peak-to-peak)
ripple arm
frequency adjust
(0-20 Hz)
phase adjust
tiltsgenerator
raises andlowers ripple
arms
three pronged clip formounting actuatorforearms
Mechanical Ripple Generator Assembly Control and Details
phase lock
The WA-9777 Basic Ripple Generator includes the
following:
mechanical ripple generator assembly with rod
clamp
small rubber actuators (3)
large rubber actuators (3)
plane wave actuator bar with screws (8) for creating
multiple point sources
forearms (2) for attaching plane wave actuator or
rubber actuators to the mechanical ripple generator
assembly
9VDC power adapter
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4
Basic Ripple Tank System 012-05846A
Assembly
steel tank frame
ripple tank leg (4)
Figure 1: Ripple Tank Assembly
rubber stopperglass tank withrubber gasket
leveling foot
When filling the tank with water, the water level must be
above the step on the rubber boundary so reflections will
be minimized. Most experiments require from 1.2 liters to
2.0 liters of water. The tank can be leveled by checkingthe depth of the water in three of the four corners.
Cleanup and Storage
To empty the water from the tank, place a container under
the drain hole and pull the plug. When the water stops
flowing out of the hole, raise the corner of the tank oppo-
site the hole so the rest of the water will drain out. Use a
towel to dry the glass tank. Replace the plug for storage.
Store the glass tank in its custom shipping box.
WA-9773 Ripple Tank
Assembly of the Tank
To assemble the tank, screw a leg into the bottom of eachof the four corners of the tank frame. Place the glass plate
into the top of the tank frame so the rubber sides form the
basin for the water. If the glass plate does not touch the
tank frame at all four corners, use the leveling feet on the
legs of the tank to reshape the frame to fit the glass plate.
Insert the rubber stopper into the drain hole in the glass
plate and push down on it to make sure the water will not
leak out. See Figure 1.
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5
012-05846A Basic Ripple Tank System
WA-97
76
50WHA
LOGEN
POINT
LIGHT
SOURCE
Figure 2: WA-9776 50W Point Light
Source Assembly
ME-8735 large rodstand
(not included)
ME-873890cm rod
(not included)
SE-9444 rightangle rod clamp(not included)
light sourceassembly with
rod clamp
ME-8736 45cm rod(not included)
FREQUENCY
AMPLITUDEADJUST
A
MIN
MAX
7
6
5
4
3
2
1
G
BC
D
E
F
HI
J
PHASE360
270
180
900
Figure 3: WA-9777 Ripple Generator
ME-8735 large rodstand
(not included)
mechanical ripplegenerator assembly
with rod clamp
ME-873890cm rod
(not included)
WA-9776 50W Halogen Point Light Source
Mounting the Light Source
All experiments require a point light source such as the
PASCO Halogen Light Source (WA-9776).
A PASCO ME-8735 Large Rod Stand and either theME-8738 (90cm) or ME-8741 (120cm) support rod are
needed to mount the light source. See Figure 2. Mount the
light source above the ripple generator on the same rod
stand. It is preferable to have the light source at least 50
cm above the tank. At this distance, the halogen filament
more closely approximates a point light source and the
waves cast well-defined shadows onto the paper on the
table beneath the ripple tank. See Figure 2.
WA-9777 Ripple Generator
Mounting the Ripple Generator
Mount the ripple generator below the light source on the
same lab stand. See Figure 3. The use of two support rods
mounted side-by-side in the large base with a cross-sup-
port will provide the ripple generator a particularly sturdy
support. Mount the ripple generator on the support rod
using the generators rod clamp. To prevent any unwanted
vibrations, the ripple generator should be positioned just
above the edge of the tank so it does not make contact
with the tank. The ripple generator is powered by a 9-Volt
adapter which plugs into the side of the generator.
NOTE:When the PASCO ME-8735 Large RodStand is used setting up the WA-9775 Basic Ripple
Tank System, the complete system can be setup us-
ing a single rod stand. For best results, setup the
equipment as shown in Figure 6.
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6
Basic Ripple Tank System 012-05846A
Generator Attachments
Attachments of various sizes and shapes are sup-
plied with the ripple generator to create different
types of waves. The system includes a plane-wave
attachment and two different sizes of point source
attachments: large and small rubber actuators. Theplane wave actuator is a bar that can be attached to
the ripple generator by inserting the actuator fore-
arms from the ripple arms of the ripple generator
assembly into the holes in the plane wave actuator
bar. Note the orientation of the bar with respect to
the tank. See Figure 4.
The ripple generator arms are the two molded plastic
arms that protrude out of the front of the ripple gen-
erator. Each ripple generator arm has a bent wire
(actuator forearm) that must be inserted into the
three pronged clip at the tip of each ripple arm. SeeFigure 4. The actuator forearms can be used to adjust the
height of the actuator by sliding the forearm up or down
in the ripple generator arm. The plane wave actuator bar
also has screws which act as multiple point sources when the
plane wave actuator bar is inverted on the actuator arms.
The point sources (small and large rubber actuators) are
rubber disks that slide onto the actuator forearms on the
ripple generator. A total of four different sizes of point
sources can be achieved using the two rubber actuators
supplied. The four sizes include the large rubber actuator,
the small rubber actuator used with its larger side down,
the small rubber actuator used with its smaller down, and
the actuator forearm used without any attachment. In gen-
eral, the greater the frequency of the ripple generator, the
smaller the point source attachment should be to produce
the best looking circular waves. Please see the Equip-
ment section illustrations.
Height Adjustment
The ripple generator may be tilted left-to-right or front-to-
back using the three thumb nuts on the top of the ripple
generator. With these thumb nuts, fine adjustments in the
depth of the actuators can be made without moving the
whole ripple generator on its rod stand or moving the
bent-wire actuators. Screwing the front thumb nut down
will raise the actuator out of the water. Screwing one of
the back thumb nuts down will lower the actuator on the
side opposite to the thumb nut that is used.
Frequency Adjustment
The frequency of the ripple generator can be adjusted
from 0 Hz to 20 Hz. The frequency knob is marked with
the letters A (0 Hz) through J (20 Hz) in approximately
even intervals so the user may repeat experiments by
*Diagram from Water Waves in a Ripple Tank by Goro
Kuwabara, Toshihiro Hasegawa, and Kimitoshi Kono, Ameri-
can Journal of Physics, Vol. 54, No. 11, November 1986, page
1003.
FREQUENCYAMPLITUDE ADJUST
A
MINMAX
7 6 5 4 3 2 1
G
B C
D
E
F
HIJ
PHASE360
270
18090
0
water
WA-9773Ripple Tank
mechanicalripple generator
assemblyheight adjustment
thumbnuts
ripple arm
actuator
forearm
plane waveactuator bar
Figure 4: Ripple Generator with Plane Wave Attachment
knowing to what letter the frequency was set. In general it
is necessary to use frequencies less than 5 Hz for refrac-
tion experiments because the speed of the waves for dif-
ferent depths is the same for frequencies above about 10
Hz. See Figure 5.
Amplitude Adjustment
The amplitude of each actuator arm can be adjusted by
loosening the thumb nut on the amplitude adjust and slid-
ing the indicator to the desired position and tightening the
thumb nut at this position. The amplitude can be varied
from about 1 mm to 4 mm peak-to-peak. This is indicated
on a scale of 1 (minimum) to 7 (maximum) on the label.
Frequency (Hz)1
Velocity(cm/sec)
2 5 1010
20
30
50
70
20 30
Figure 5: Dispersion Relation of Waves as aFunction of Depth*
2cm
1cm
0.5cm
0.2cm
h = 4cm
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7
012-05846A Basic Ripple Tank System
FREQUENCYAMPLITUDE ADJUST
A
MINMAX
7 6 5 4 3 2 1
G
B C
D
E
F
HIJ
PHASE360
270
18090
0
Figure 6: Mounting the Complete WA-9775 Basic Ripple Tank System using one ME-8735 Large Rod Stand
50cm
WA-9777 BasicRipple Generator
ME-8735 LargeRod Stand
SE-9444 rightangle rod clamp(2, not included)
ME-8741 120cm rod(2, not included)
ME-8736 45cm rod(not included)
WA-9773 RippleTank
WA-9776 50W Halogen
Point Light Source
The numerical reference allows the user to set the same
amplitude on each side by setting each indicator to the
same number.
Phase Difference
The phase difference between the two actuators can be ad-
justed from zero to 360 degrees using the phase knob nearthe frequency knob on the side of the ripple generator.
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8
Basic Ripple Tank System 012-05846A
Notes:
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9
012-05846A Basic Ripple Tank System
Experiment 1: Reflection
EQUIPMENT REQUIRED
Ripple Tank (WA-9773) straight barrier (triangular refractor)
curved barrier (concave refractor)
clear metric rule
50W Halogen Point Light Source (WA-9776)
Ripple Generator (WA-9777)
plane wave actuator bar
protractor
drawing compass
paper (40 cm x 40 cm)
rod stand (90 to 120 cm long)
PurposeTo study the reflection of a plane wave from different shaped barriers.
Theory
When a ray reflects off a surface, the angle of incidence
is the angle between the incoming (incident) ray and the
normal. The angle of reflection is the angle between the
outgoing (reflected) ray and the normal. The normal is a
line that is perpendicular to the surface. See Figure 1.1.
Wave fronts are perpendicular to the rays.
Setup
Type of Actuator: Plane Wave Actuator Bar
Water Depth: 5mm
Actuator Depth: touching water surface
Frequency: 5-10Hz
Amplitude: maximum
Fill the tank with water to a depth of about 5 mm so the water is just above the step in the rubber
gasket. The depth of the water must be less than the thickness of the plastic barrier.
Level the tank.
Put the plane wave actuator bar on the ripple generator. Adjust the height of the ends of the bar
so the bar is level with the surface of the water. Then lower the whole ripple generator until the
bottom of the bar is submerged about half way down.
Loosen the phase lock knob, set the phase setting to zero, retighten the phase lock knob.
Set the amplitude to the maximum setting.
Set the frequency to setting C.
Plug in the ripple generator and the light source.
Figure 1.1: Definition of Angles
wav
efront
incidentrayrefle
cted
ray
normal
ri
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Part I: Reflection Using a Straight Barrier
Figure 1.2: Position of Straight Barrier
mechanical ripplegenerator
plane waveactuator bar
straight barrier(triangular reflector)
ripple tank
Procedure
Place the straight barrier in the water at an angle to the incoming plane waves. See Figure 1.2.
On the paper below the tank, place the metric rule parallel to the plane waves that are incoming to
the barrier. Make a line to show the incoming wave front.
Align the rule with the reflected wave and make a line to show the reflected wave.
Trace the position of the straight barrier.
Turn off the light source and ripple generator.
Draw a line that is perpendicular to the incoming wave front. Extend it to the straight barrier. This
represents the incoming ray so draw an arrow on it pointing toward the barrier.
Draw a line from the point where the incoming ray strikes the barrier so it crosses the reflected
wave front at a right angle. This represents the reflected ray so draw an arrow on it pointing away
from the barrier.
Draw the normal (perpendicular) line at the point of reflection on the barrier.
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Measure the angle of incidence, i, and the
angle of reflection, r. What is the relationship
between these angles? Record the results in
Table 1.1.
Repeat this procedure with the barrier at a different angle.
Part II: Reflection Using a Curved Barrier
Angle of Incidence
Angle of Reflection
Trial #1 Trial #2
Table 1.1 Reflection Results
Procedure
Replace the straight barrier with the circular barrier and position as shown in Figure 1.3.
Trace the position of the circular barrier on the paper.
Mark the position on the paper where the reflected waves converge.
Turn off the ripple generator.
Use the tip of your finger to produce a circular pulse at the marked position where the waves
converged.
What is the shape of the pulse after it is reflected off the barrier?
mechanical ripple
generator plane waveactuator bar
ripple tank
Figure 1.3 Position of Circular Barrier
circular barrier(concave refractor)
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To locate the center of the circle, use the drawing compass to trace the circular shape of the bar-
rier. Mark the center of the circle and measure the radius.
How is the radius of the circle related the distance between the circular barrier and the point
where the reflected waves converged?
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Experiment 2: Refraction
EQUIPMENT REQUIRED
Ripple Tank (WA-9773) triangular refractor
concave refractor
convex refractor
clear metric rule
50W Halogen Point Light Source (WA-9776)
Ripple Generator (WA-9777)
plane wave actuator bar
9 identical coins (to adjust the height of the triangular refractor)
paper (40 cm x 40 cm)
rod stand (90 to 120 cm long)
PurposeThe purpose is to show how waves bend as they pass from one medium to another.
Theory
As a wave passes from one medium to another, it changes speed. If it slows down, the wave will
bend toward the normal as shown in Figure 2.1. This bending is called refraction.
Figure 2.1: A Wave Slowing Down
medium #2
medium #1
interface between twomediums
Setup
Type of Actuator: Plane Wave Actuator Bar
Water Depth: 10mm
Actuator Depth: deep as possible
Frequency: setting A or B (2-5Hz)Amplitude: maximum
Fill the tank with water to a depth of about 10 mm.
Level the tank.
Put the plane wave actuator bar on the ripple generator. Adjust the height of the ends of the bar
so the bar is level with the surface of the water. Then lower the whole ripple generator until the
bottom of the bar is submerged as far down as possible, leaving room for the bar to oscillate. If
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the bar hits the bottom of the tank when it oscillates, raise it until it just barely clears the bottom
of the tank while oscillating.
Loosen the phase lock knob, set the phase setting to zero, retighten the phase lock knob.
Set the amplitude to the maximum setting.
Set the frequency to setting A or B.
Plug in the ripple generator and the light source.
Part I: Refraction Using a Straight Refractor
mechanical ripplegenerator
plane waveactuator bar
triangular refractor
ripple tank
Figure 2.2: Position of Triangular RefractorProcedure
Place the triangular refractor in the water at an angle to the incoming plane waves. See Figure 2.2.
To simulate two different mediums, the depth of the water must change. Raise the triangular
refractor by placing an equal number of coins under each corner of the triangle. Adjust the height
in this manner so the depth of the water on top of the triangle is only 2 to 3 mm.
On the paper below the tank, place the metric rule parallel to the plane waves that are incoming to
the refractor. Make a line to show the incoming wave front.
Align the rule with the refracted wave over the triangle and make a line to show the refractedwave.
Trace the position of the edge of the triangular refractor that the wave hits.
Turn off the light source and ripple generator.
Draw a line that is perpendicular to the incoming wave front. Extend it to the edge of the triangu-
lar refractor. This represents the incoming ray so draw an arrow on it pointing toward the triangle.
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Draw a line frm the point where the incoming ray strikes the triangle so it crosses teh reefracted
wave front at a right angle. This represents the refracted ray so draw an arrow on it showing
which way the wave is traveling.
Draw the normal (perpendicular) line at teh point of refraction on the triangle.
When the wave goes from the deep water to the shallow water in the triangle area, does the wave
bend toward or away from the normal?
When the wave goes from the deep water to the shallow water in teh triangle area, does teh wave
speed up or slow down?
Part II: Refraction Using Curved Refractors
Procedure
Replace the triangular refractor with the convex refractor, placing it a few centimeters from the
plane wave generator.
Turn on the ripple generator and trace the pattern seen.
Measure the focal length of the lens. This is the distance from the center of the lens to the place
where the plane waves are focused.
Replace the convex refractor with the concave refractor and trace the pattern seen.
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Notes:
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Experiment 3: Diffraction
EQUIPMENT REQUIRED
Ripple Tank (WA-9773) triangular refractor
long straight reflector (2)
short straight reflector
clear metric rule
50W Halogen Point Light Source (WA-9776)
Ripple Generator (WA-9777)
plane wave actuator bar
paper (40 cm x 40 cm)
rod stand (90 to 120 cm long)
Purpose
The purpose of this experiment is to determine how the diffraction pattern changes as the slit
width and the wavelength are varied.
Setup
Type of Actuator: Plane Wave Actuator Bar
Water Depth: 7mm
Actuator Depth: touching water surface
Frequency: 10Hz (setting E)
Amplitude: setting 4
Fill the tank with water to a depth of about 7 mm so the water is just above the step in the rubber
gasket. Level the tank.
Put the plane wave actuator bar on the ripple generator. Adjust the height of the ends of the bar
so the bar is level with the surface of the water. Then lower the whole ripple generator until the
bottom of the bar just touches the surface of the water.
Loosen the phase lock knob, set the phase setting to zero, retighten the phase lock knob.
Set the amplitude to setting #4.
Set the frequency to setting E.
Plug in the ripple generator and the light source.
Procedure
Place the two long straight reflector about 3 cm apart in the water as shown in Figure 3.1.
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On the paper below the tank, trace the reflectors and roughly trace the angle that the waves spread
out when they pass through the slit. Make a sketch of the wave pattern here.
Change the slit width to about 1.5 cm by sliding the two reflectors closer together.
On the paper trace the new angle that the waves spread through. Is this angle more or less than the
angle for the wider slit?
Figure 3.1 Position of Straight Barriers
3cm
straight barriers(long straight reflectors)
ripple tank
mechanical ripplegenerator plane wave
actuator bar
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Keeping the same slit width of about 1.5 cm, increase the frequency of ripple generator to setting
J.
How does increasing the frequency affect the wavelength?
How does increasing the frequency change the spread angle?
Replace the slit with the mini straight reflector. Remove the two long straight reflectors. See
Figure 3.2.
ripple tank
mechanical ripplegenerator plane wave
actuator bar
straight barrier(mini straight reflector)
Figure 3.2: Diffraction for a Solid Object
Sketch the resulting wave pattern here.
How does this pattern compare to the same-size slit pattern?
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Notes:
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Experiment 4: Interference
EQUIPMENT REQUIRED
Ripple Tank (WA-9773) long straight reflector (2)
short straight reflector
clear metric rule
50W Halogen Point Light Source (WA-9776)
Ripple Generator (WA-9777)
plane wave actuator bar
paper (40 cm x 40 cm)
rod stand (90 to 120 cm long)
Purpose
The purpose of this experiment is to determine how the interference pattern changes as the slit
separation and the wavelength are varied.
Theory
When a wave passes through two slits, the positions of maximum intensities are given by
dsin=m(where m= 0, 1, 2,)
where d is the slit separation,is the angle between maxima, is the wavelength, and m is
the order. See Figure 4.1.
screenslits
a
d
maximum
maximum
Figure 4.1: Double-slit
SetupType of Actuator: Plane Wave Actuator Bar
Water Depth: 7mm
Actuator Depth: touching water surface
Frequency: 10Hz (setting E)
Amplitude: setting 4
Fill the tank with water to a depth of about 7 mm so the water is just above the step in the rubber
gasket.
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Level the tank.
Put the plane wave actuator bar on the ripple generator. Adjust the height of the ends of the bar so
the bar is level with the surface of the water. Then lower the whole ripple generator until the
bottom of the bar just touches the surface of the water.
Loosen the phase lock knob, set the phase setting to zero, retighten the phase lock knob.
Set the amplitude to setting #4.
Set the frequency to setting E.
Plug in the ripple generator and the light source.
Procedure
Place the short straight reflector between the two longest reflectors to form two openings about 2
cm long as shown in Figure 4.2.
ripple tank
mechanical ripplegenerator plane wave
actuator bar
2cm
2cm
straight barriers
(long straight reflectors)
straight barrier(short straight reflector)
Figure 4.2: Position of Straight Barriers
On the paper below the tank, trace the reflectors and roughly trace the angles that the waves
spread out when they pass through the slit. Find the regions where the waves from the two slits
tend to cancel each other and find the regions where the waves add together to make waves with
higher peaks. Make a sketch of the wave pattern here.
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Figure 4.3: Interference Using Two Point Sources
ripple tank
mechanical ripplegenerator point sources
(small rubberactuators, 2)
Decrease the slit separation by the replacing the center reflector with the mini straight reflector
but keep the slit width at 2 cm.
Does the spread angle of the wave increase or decrease?
Keeping the same slit width of about 2 cm and the same slit separation, increase the frequency
of ripple generator to setting J. This decreases the wavelength. How does decreasing the wave-
length change the spread angle?
Now remove the straight barriers from the tank and replace the plane wave actuator bar with two
point sources (large end of the small rubber actuators) as shown in Figure 4.3. Using the same
settings, compare the point source wave pattern with the two-slit pattern.
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Notes:
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Experiment 5: Image Formed by a Plane Mirror
EQUIPMENT REQUIRED
Ripple Tank (WA-9773) straight barrier (triangular refractor)
clear metric rule
50W Halogen Point Light Source (WA-9776)
Ripple Generator (WA-9777)
point source (small rubber actuator)
paper (40 cm x 40 cm)
rod stand (90 to 120 cm long)
Purpose
The purpose is to show the position of the image formed by a plane mirror.
Setup
Type of Actuator: one medium point source (large side of small rubber actuator)
Water Depth: 7mm
Actuator Depth: touching water surface
Frequency: setting A (2-3Hz)
Amplitude: setting 5
Fill the tank with water to a depth of about 7 mm so the water is just above the step in the rubber
gasket.
Level the tank.
Put the point source (small rubber actuator) on the ripple generator. Adjust the height of thepoint source until it just touches the surface of the water.
Loosen the phase lock knob, set the phase setting to zero, retighten the phase lock knob.
Set the amplitude to setting #5.
Set the frequency to setting A.
Plug in the ripple generator and the light source.
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Figure 5.1: Straight Barrier
ripple tank
mechanical ripplegenerator point source
(small rubber actuator)
Procedure
Place the straight barrier in the tank as shown in Figure 5.1.
On the paper below the tank, mark the position of the point source and the position of the straight
barrier. Measure the perpendicular distance from the barrier to the point source.
Record this distance here:___________________
Lay a ruler on the paper with one end of the ruler on any point on the line that indicates the bar-
rier. Orient the ruler so it crosses the reflected wave fronts at a right angle. Draw a line along the
ruler in this position.
Move the end of the ruler to a new point on the barrier line and orient it so it again crosses the
reflected wave fronts at a right angle. Draw a line along the ruler in this new position.
Extend the two ruler lines until they cross. The point where they cross is the center of the re-
flected circles. This center represents the position of the image.
Is the image located on the same side of the barrier as the point object?___________
Measure the perpendicular distance from the barrier to the image of the point source. Record this
distance here:___________________
How is this distance related to the distance between the point source and the barrier?
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Experiment 6: Dependence of WaveSpeed on Water Depth
EQUIPMENT REQUIRED
Ripple Tank (WA-9773)
straight barrier (triangular refractor)
clear metric rule
50W Halogen Point Light Source (WA-9776)
Ripple Generator (WA-9777)
plane wave actuator bar
protractor
6 identical coins (to adjust the height of the triangular refractor)
paper (40 cm x 40 cm)
rod stand (90 to 120 cm long)
stopwatch
Purpose
The purpose is to determine the dependence of wave speed on water depth and to show how
waves break on a shore.
Setup
Type of Actuator: Plane Wave Actuator Bar
Water Depth: 10mm
Actuator Depth: touching water surface
Frequency: setting B (4Hz)
Amplitude: maximum
Fill the tank with water to a depth of 10 mm.
Level the tank.
Put the plane wave actuator bar on the ripple generator. Adjust the height of the ends of the bar
so the bar is level with the surface of the water. Then lower the whole ripple generator until the
bottom of the bar just touches the surface of the water.
Loosen the phase lock knob, set the phase setting to zero, retighten the phase lock knob.
Set the amplitude to the maximum setting.
Set the frequency to setting B.
Plug in the ripple generator and the light source.
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Figure 6.1: Experiment Setup
mechanical ripplegenerator
plane waveactuator bar
triangular reflector
ripple tank
water
Part I: Breaking Waves On Shore
Procedure
Place the triangular refractor in the tank as shown in Figure 6.1. Place several coins under one
corner of the triangle so it slants up out of the water. This causes the water depth to change and
forms the beach.
Observe the plane waves as they approach the beach.
At what angle do the wave fronts meet the beach?
Sketch the path of the wave fronts as they travel from the ripple generator to the shore.
glass
coins
coins
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Part II: Wave Speed
Procedure
Lay the clear plastic metric rule in the water so it is perpendicular to the wave fronts. Follow the
movement of a wave front by running your finger along the projected image of the ruler on thepaper below the tank, keeping your finger pointed at a particular wave front. Use the stopwatch
to time how long it takes your finger to run the length of the ruler.
Table 6.1: Wave Speed Versus Frequency
TimeFrequency Setting Wave Speed
Use
v = d/tto calculate the wave speed. Record in Table 6.1.
Change the frequency to setting D and find the speed of the wave again. Record in Table 6.1.
In order to produce a good wave, it may be necessary to decrease the amplitude as the frequency
is increased.
Change the frequency to setting G and find the speed of the wave again. Record in Table 6.1.
How does speed of the wave depend on frequency?
Return the frequency to setting B and set the amplitude for maximum. Record the wave speedpreviously found for the 10 mm deep water in Table 6.2.
Drain some of the water so the depth is 7 mm. Find the wave speed for this new depth. Record
in Table 6.2.
Repeat the last step for depths of 5 mm and 2 mm.
Table 6.2: Wave Speed Versus Water Depth
TimeDepth of Water (mm) Wave Speed
10
7
5
2
On a separate sheet of graph paper, plot wave speed as a function of the water depth.
How does speed of the wave depend on the depth of the water?
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Notes:
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Technical Support Feedback
Feedback
If you have any comments about the product or manual,please let us know. If you have any suggestions on
alternate experiments or find a problem in the manual,
please tell us. PASCO appreciates any customer feed-
back. Your input helps us evaluate and improve our
product.
To Reach PASCO
For technical support, call us at 1-800-772-8700 (toll-
free within the U.S.) or (916) 786-3800.
fax: (916) 786-3292
e-mail: [email protected]
web: www.pasco.com
Contacting Technical Support
Before you call the PASCO Technical Support staff, it
would be helpful to prepare the following information:
If your problem is with the PASCO apparatus, note:
Title and model number (usually listed on the
label);
Approximate age of apparatus;
A detailed description of the problem/sequence of
events (in case you cant call PASCO right away,
you wont lose valuable data);
If possible, have the apparatus within reach when
calling to facilitate description of individual parts.
If your problem relates to the instruction manual,
note:
Part number and revision (listed by month and
year on the front cover);Have the manual at
hand to discuss your questions.
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