Pasco Scientific SE-9717 User manual

© 1999 PASCO scientific
Instruction Manual and
Experiment Guide for
the PASCO scientific
Model SE-9717
012-07190B
MAGDEBURG PLATES
Includes
Teacher's Notes
and
Typical
Experiment Results
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cc

Magdeburg Plates 012–07190B
The exclamation point within an equilateral
triangle is intended to alert the user of the
presence of important operating and
maintenance (servicing) instructions in the
literature accompanying the device.

012–07190B Magdeburg Plates
Table of Contents
Section Page
Copyright, Warranty, and Equipment Return ............................................................................... ii
Introduction ................................................................................................................................1
Equipment ................................................................................................................................. 1
Theory ....................................................................................................................................... 2
Basic Setup ................................................................................................................................3
Setup with ScienceWorkshop and a Pressure Sensor ............................................................... 4
Operation................................................................................................................................... 4
Operation with ScienceWorkshop ............................................................................................ 5
Cautions (Safety)....................................................................................................................... 5
Maintenance .............................................................................................................................. 6
Activities
Activity 1: Determining the total force on the plates due to atmospheric pressure ............... 7
Activity 2: Experimentally determining the force holding the plates together ...................... 9
Activity 3: Measuring the vacuum and observing its rate of decay using
ScienceWorkshop .............................................................................................. 10
Activity 4: Determining the effect of air pressure on boiling point of water ....................... 11
Activity 5 Investigating the effect of air pressure on the size of a balloon ......................... 13
Activity 6: Investigating the effect of air pressure on a suction cup .................................... 13
Teacher’s Notes ............................................................................................................... 14–16
Appendix
Technical Support .................................................................................................... Back Cover
i

ii
Copyright Notice
The PASCO scientific 012-07190A Magdeburg
Plates manual is copyrighted and all rights
reserved. However, permission is granted to non-
profit educational institutions for reproduction of
any part of the 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 equipment after repair will be paid by
PASCO scientific.
Copyright,Warranty, and Equipment Return
Please—Feel free to duplicate this manual
subject to the copyright restrictions below.
Credits
Author: Jim Housley
Editor: Sunny Bishop
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.
➤➤
➤➤
➤ NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION FROM PASCO.
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:
➀The packing carton must be strong enough for the item
shipped.
➁Make certain there are at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.
➂Make 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: [phone]
FAX: [phone]
e-mail: [email protected]
Web site www.pasco.com

012–07190B Magdeburg Plates
1
Introduction
Equipment
Included:
The PASCO SE-9717 Magdeburg Plates can be used to illustrate the concept of
atmospheric pressure. Their flat plate design permits the calculation of forces
using simple algebraic mathematics. In contrast, the traditional Magdeburg
hemispheres required calculus for the calculation of the forces involved.
The transparency of the plates allows students to visualize the small chamber that
is defined by the O-ring.
The choice of smaller and larger chambers through the use of the small and large
O-ring further illustrates the concept of the pressures involved in holding the
plates together.
The syringe and one-way check valve system constitute an inexpensive vacuum
pump.
An extra connector is provided to permit the plates to be connected to a PASCO
Pressure Sensor, allowing the monitoring of the pressure inside the chamber.
Optional Accessories
The optional Magdeburg Accessories are used to illustrate the effect of air
pressure on the boiling temperature, on the size of a balloon, and on the suctional
ability of a suction cup.
Part Label Part Name
Aplate with hose connector
B plate without hose connector
C large diameter O-ring
D small diameter O-ring
E tubing with check valve
F tubing with T and check valve
G 60 cc syringe
H tubing for connection with a
PASCO Pressure Sensor
Note:
Parts E, F, and G constitute the vacuum pump
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AB
C
D
E
F
G
H

Magdeburg Plates 012–07190B
2
Before the vacuum is pulled, the pressure of the air inside the plates equals the
pressure outside the plates (Figure 1a).
After the vacuum is pulled, the plates are held together with a force equal to the
total pressure outside the plates minus the residual pressure inside the plates after
the removal of air with the vacuum pump (Figure 1b).
Figure 1
(a) When no vacuum exists
inside the plates, the force
of atmospheric pressure
against the outside of the
plate equals the force
pushing from the inside.
(b) When a vacuum has
been created in the interior
chamber, the force holding
the plates together is equal
to the atmospheric
pressure
a
b
Note: Approximately 610 Newtons (137 pounds) of force are required to pull
the plates apart when the large O-ring is used.
Theory
Additional Suggested:
• Magdeburg Plate Accessories (SE-9718)
• Pressure Sensor (CI-6532 or CI-6533)
[Do not use with CI-6534 Low Pressure or CI-6559 Humidity Sensor]
•ScienceWorkshop Interface (300, 500, 700, or 750)
• computer and data acquisition software
(ScienceWorkshop or DataStudio)

012–07190B Magdeburg Plates
3
Basic
Setup
1. Connect the hose
connector on part E
to the hose
connector on part A
(Figure 2).
Figure 2
Connecting part E to part A
2. Connect part F to
part E (Figure 3).
3. Connect the syringe
to the T of part F.
4. Put O-ring on part A.
(Use either one of the
O-rings, but not
both.)
5. Place part B (plate)
on the O-ring on part
A (other plate).
A
E
Figure 3
Completing the setup
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O-ring
B
A
F
syringe
E

Magdeburg Plates 012–07190B
4
Setup with
Science-
Workshop
and a
Pressure
Sensor
To obtain qualitative information about the force required to offset atmospheric
pressure, set up the Magdeburg Plates without ScienceWorkshop.
1. Pull vacuum (usually requires 3 or 4 pulls on the syringe plunger).
Note: The vacuum deteriorates slowly, usually over a 10 – 60 minute
period.
2. Disconnect part F
from part E. (Check
valve in part E
maintains the
vacuum) (Figure 5).
3. Grasp both handles
and pull (individual
or “tug of war”).
Operation
without
Science
Workshop
Figure 5
Magdeburg Plates ready for experimentation
Figure 4
Connecting a Pressure Sensor to the vacuum line.
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to ScienceWorkshop Interface
H
E
F
Pressure Sensor
1. Connect part H to the hose connector on part A (Figure 4).
2. Connect part E to
part H.
3. Connect part F to
part E.
4. Connect the syringe
to the T of part F.
5. Connect the
Pressure Sensor to
the T on part H.
6. Put the O-ring
on part A.
7. Place part B (plate)
on the O-ring
on part A (the other
plate).

012–07190B Magdeburg Plates
5
Operation with ScienceWorkshop to obtain quantitative information about the
force required to offset atmospheric pressure, and to demonstrate the correlation
between the breaking apart of the plates and the rise in interior pressure.
1. Set up to monitor the pressure while pulling the vacuum.
2. Pull vacuum (usually requires 3 or 4 pulls on the syringe plunger).
Note: The vacuum deteriorates slowly, usually over a 10 – 60 minute
period.
3. Disconnect part E
from part F (figure 6).
4. Start recording data.
5. Grasp both handles
and pull (individual
or “tug of war”).
6. Stop recording data.
Operation
with
Science
Workshop
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Figure 6
Magdeburg Plates ready for experimentation and
monitoring of interior chamber pressure.
Pressure Sensor
H
E
to ScienceWorkshop Interface
Note: Take care to avoid jerking the Pressure Sensor when the
plates break apart.
This set is intended to be used by teachers, and their students while working
under appropriate supervision.
• Make sure students are in a safe place to do a “tug of war.” Plates will
separate suddenly, possibly throwing pullers off balance. There should be
no breakable or sharp objects or sharp corners behind the students.
• Do not tie a weight onto one handle in an attempt to pull the plates apart.
•Do not tie ropes to the handles and do a “tug of “war to pull the plates apart.
The plates will separate suddenly and will fly through the air at a very high
velocity.
(continued on next page)
Safety
Considerations
F

Magdeburg Plates 012–07190B
6
Plates and O-rings
The surfaces in the plates and the O-rings should be kept clean—free of
dust.
• Use mild dishwashing soap and water to clean.
• Clean the groove with a cotton swab.
Cautions:
• Do not use abrasives.
• Do not use organic chemicals.
• Do not try to pry the plates open with a screw driver or similar
apparatus.
• Do not apply plate A to any surface that might be damaged, particularly
glass or skin.
Note: Vacuum grease should not be necessary on the O-rings or
connectors, and use of it will attract dust and dirt.
Syringe
• Glycerin may be used on the plunger, but usually no lubricant is required.
Caution:
• Do not use any petroleum-based lubricant on the syringe. The plunger
is very intolerant to petroleum-based substances.
Maintenance
Generally...
Please teach and expect safe behavior in your classroom and lab. Safety
considerations call for supervision of students at all times, use of safety
eyeware, no horseplay, no unauthorized experimentation, immediate
reporting to the instructor of accidents or breakage, among others.
More Specifically...
Any liquids entering the pump are apt to be discharged as a mist or spray.
Only safe liquids such as water should be allowed to be used in association
with the pump, and safety eyeware is definitely required.
Evauate the chamber only using both plates. Attempting to evacuate the
chamber while plate A is in contact with other surfaces could result ing
damage. Severe injury will result from evacuating the chamber while in
contact with skin.
Do not use the apparatus if the plates have become cracked or otherwise
damaged.
Safety
Considerations
(continued)

012–07190B Magdeburg Plates
7
Determining the total force on the plates is equal to the force of
atmospheric pressure on the plates
Introduction
The total force on the plates is the total air pressure on the surface area defined
by the O-ring. You will need to find the area inside the contact points of the O-
ring. Then you can use the air pressure in your area (or use a typical value at sea
level to find the approximate force). You will then use the relationship:
FNET = (FAP - FR) * πr2
Where FNET = net force on the Magdeburg Plates
FAP = total atmospheric pressure
FR= residual pressure in the evacuated chamber
πr2= surface area enclosed by the O-ring
to determine the theoretical force that holds the Magdeburg Plates together.
Procedure
1. Determine the diameter of the surface enclosed by the O-ring by
measuring the outer and inner diameters of the O-ring. Then find the
average of these two diameters. See Figure 1.1
2. Assemble the Magdeburg Plates with the connection for
ScienceWorkshop (Figure 1.2), and pull a vacuum in the interior
chamber with the vacuum pump.
3. Using a ScienceWorkshop interface and Pressure Sensor, measure the
pressure inside
the chamber (or
assume it is 5
kPa).
4. Measure the
atmospheric
pressure using a
barometer, a
PASCO CI-6531
Activity 1
Figure 1.1
Measuring the diameter of
the surface enclosed by
the O-ring
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Pressure Sensor
H
E
to ScienceWorkshop Interface
F
Figure 1.2
Experiment Setup for Activity 1
d
2
d
1
2
+= average
d
1
d
2

Magdeburg Plates 012–07190B
8
Barometer Sensor, or a PASCO CI-6532 Absolute Pressure Sensor.
Note: If you are not near sea level and you use a barometer or a media
report of barometric pressure, be sure that the reading has not been
“corrected to sea level” as is commonly done. A call to a local weather
station should request “station pressure not corrected to sea level.”
101kPa is a typical value at sea level.
5. If necessary, convert the atmospheric pressure readings to kPa (refer to
Physics reference materials, if necessary).
6. Calculate the Net Force that holds the plates together using the
relationship:
FNET = (FAP - FR) * πr2
Note: 1 Pascal = 1 N/m2 and 1 lb is approximately equal to 4.45 N.
(Try to pull the plates apart to appreciate the amount of this force.)
7. Repeat the calculation for the small O-ring.

012–07190B Magdeburg Plates
9
Experimentally determining the force holding the plates together
(smallO-ring)
1. Assemble the plates using the small O-ring and pull a vacuum in the
inter-plate space (Figure 2.1).
2. Have a light, strong student stand on a bathroom scale (Figure 2.2)
holding one handle of the Magdeburg Plates.
3. A strong person
will kneel in
front and pull
on the second
handle.
4. A third person
will monitor the
readout on the
scales to note
the highest
value.
5. The two
students will
pull the plates
apart with a
slow, and
steadily
increasing force
while the third
person notes the
highest value.
6. Calculate the
force required to break the plates (Total weight - person’s weight and
the weight of the Magdeburg plates)
7. If the scale read in pounds, multiply by 4.45 to get newtons. If it reads
in kg, multiply by 9.8 to get newtons.
Compare with the calculated force in activity 1.
Note: Due to the large force required to break the plates sealed with the
large O-ring, this experiment cannot be done — or would be dangerous
to do — with the large O-ring.
Activity 2
Figure 2.1
Experimental Setup for
Activity 2
Figure 2.2
Applying the external force to pull the plates apart
185
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O-ring
E
F

Magdeburg Plates 012–07190B
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Measuring the vacuum pulled and observe the rate of decay using
ScienceWorkshop
Introduction
You can use a ScienceWorkshop Interface, computer, and Pressure Sensor to
monitor the pressure in the chamber between the plates.
Procedure
1. Assemble the Magdeburg plates so the chamber pressure can be
monitored with a Pressure Sensor and ScienceWorkshop Computer
Interface (Figure 3.1)
2. Set up the
Pressure Sensor
in your data
acquisition
software
(DataStudio or
ScienceWorkshop
and open a
Graph display.
3. Set the
sampling rate
on the Pressure
Sensor to 1
sample/s.
4. Start collecting
data.
5. Pull a vacuum
in the chamber
with the syringe.
6. Allow the plates to sit undisturbed for a few minutes.
7. Every minute or so, try to break the plates apart.
8. Note the pressure at which you were successful at breaking apart the
plates, and calculate the force that was required. (Use the procedure
detailed in Activity 1.)
Note: When using the CI-6533 Differential Pressure Sensors, you must subtract the
atmospheric pressure at your location by measuring it with a mercury barometer, with
a CI-6531 Barometer, or by calling the local weather bureau. If you are not near sea
level, be sure that the reading has not been “corrected to sea level” as is commonly
done. A call to a local weather station should request “station pressure not corrected
to sea level.” 101kPa is a typical value at sea level.
Activity 3
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Pressure Sensor
H
E
to ScienceWorkshop Interface
F
Figure 3.1
Experiment Setup for Activity 3

012–07190B Magdeburg Plates
11
Activities with the Magdeburg Plate Accessories
Determining the effect of air pressure on the boiling temperature
of water
Introduction:
Boiling occurs when a liquid reaches a temperature at which the vapor pressure
of the liquid equals the air pressure. The vapor pressure of the liquid is depen-
dent on both the air pressure and the temperature of the liquid. Normally, we
make a liquid boil by heating it to increase the kinetic energy of the molecules.
However, in this experiment, we will make the liquid boil by adjusting the air
pressure rather than the temperature of the liquid.
Procedure
1. Assemble the Magdeburg Plates and the extra cylinder, plate, and O-
ring from the Accessories kit as shown in Figure 4.1.
Note: Fit the O-rings into the grooves on the plate, cylinder, and base.
Activity 4
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F
E
O-ring
O-ring
accessory
cylinder
accessory
plate
cup with hot
liquid (coffee)
Figure 4.1
Experiment setup for Activity 4

Magdeburg Plates 012–07190B
12
Optional Procedure:
You can also include a connection to an Absolute Pressure Sensor to
monitor the pressure inside the chamber as in Figure 4.2.
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Pressure Sensor
to ScienceWorkshop
Computer Interface
E
H
F
Figure 4.2
Optional setup with ScienceWorkshop and a Pressure Sensor
2. Fill the plastic cup halfway with hot coffee or very hot tap water.
3. Measure the temperature of the liquid.
4. Start recording data if you are monitoring the pressure, and pull a
vacuum with the syringe. Watch the liquid carefully. What do you
observe?
5. What do you think is happening to the temperature of the liquid?
6. Loosen the connection to A slowly to release the vacuum, then measure
the temperature of the liquid. A quick release of the vacuum may cause
the hot liquid to splatter.
Hint: Apply
pressure to the top
plate during the first
few strokes of the
plunger until a
vacuum starts to
form.

012–07190B Magdeburg Plates
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Investigating the effect of air pressure on the size of a balloon.
Procedure:
1. Set up the Magdeburg
Apparatus as described in
Activity 4, replacing the cup
of hot liquid a balloon.
2. Inflate the balloon slightly so
the rubber is almost tight but
not stretched. Tie off the neck.
3. Pull a vacuum and notice the
size of the balloon.
Note: You can also use the
bubble-wrap included in the
Accessories kit in this experiment.
Investigating the effect of air pressure on a suction cup
1. Put the suction cup from the Accessories kit on the underside of the top
plate of the chamber.
2. Pull a vacuum and observe the result.
Activity 5
Figure 5.1
Setup for Activity 5
Activity 6
balloon

Magdeburg Plates 012–07190B
14
Activity 1
Sample data:
outside diameter of the large O-ring = 9.5 cm
inside diameter of the large O-ring = 8.5 cm
average of inside and outside diameter = 9.0 cm
Net Force = (atmospheric pressure - pressure inside the chamber) * π* (9.0 cm/2)2
Net Force = (101 KPa - 5 KPa) * π* (9.0 cm/2)2
Net Force = (96 KPa) * 3.14 * (9.0 cm/2)2
(1 Pascal = 1 N/m2 , and cm is meters x 10-2)
Net Force = (96 x 103N/m2) * 3.14 * (9.0 m x 10-2/2)2
Net Force = 610 N (approximately 137 lb or the weight of a 62 kg object)
(1 lb is approximately equal to 4.45 N; 1 kg is approximately 9.8 N)
Net Force = 137 pounds
Calculation with the small O-ring
outside diameter of the small O-ring = 6.0 cm
inside diameter of the small O-ring = 5.0 cm
Using the procedures and assumptions from the above example
Net Force = (96 x 103N/m2) * 3.14 * (5.5 cm x 10-2/2)2
Net Force = 228 N (approximately 51 lb or the weight of a 23 kg object)
Teacher’s
Notes

012–07190B Magdeburg Plates
15
Figure TN_1
Sample data for Activity 3
Activity 3

Magdeburg Plates 012–07190B
16
Activity 4
Result: The coffee will boil when you have created at strong vacuum (about 20
pulls on the syringe plunger). The temperature of the coffee will decrease after
boiling. Boiling is endothermic.
Figure TN_2
Sample data for Activity 4
Activity 5
The balloon will start expanding visibly when the pressure reaches about 60
kPa and will continue to expand until the maximum vacuum has been
reached or until the balloon blocks the hose port.
Activity 6
The suction cup will fall off when a pressure of about 50 kPa is reached.