Pasco Specialty And Mfg Equipopotential Field Mapper Pk 9023 Users Manual 0

2015-02-06

: Pasco-Specialty-And-Mfg Pasco-Specialty-And-Mfg-Equipopotential-And-Field-Mapper-Pk-9023-Users-Manual-516945 pasco-specialty-and-mfg-equipopotential-and-field-mapper-pk-9023-users-manual-516945 pasco-specialty-and-mfg pdf

Open the PDF directly: View PDF .
Page Count: 18

Instruction Manual and

Experiment Guide for

the PASCO scientific

Model PK-9023

012-04346B

05/91

10101 Foothills Blvd. • P. O. Box 619011 • Roseville, CA 95661-9011 USA

Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040

scientific

Instructional Manual and

Experiment Guide for the

PASCO scientific Model

PK-9023

FIELD MAPPER

10101 Foothills Blvd. • P. O. Box 619011 • Roseville, CA 95661-9011 USA

Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040

scientific

Instructional Manual and

Experiment Guide for the

PASCO scientific Model

PK-9023

FIELD MAPPER

EQUIPOTENTIAL AND

FIELD MAPPER

012-04346B

scientific

Section Page

Introduction ...................................................................................................... 1

Equipment......................................................................................................... 1

Equipment Setup............................................................................................... 2

Experiments

Parallel Plate Capacitor ........................................................................ 4

Point Source and Guard Ring ............................................................... 4

Dipoles of Opposite Charge ................................................................. 5

Dipoles of Like Charge......................................................................... 5

Floating Electrode................................................................................. 6

Floating Insulator.................................................................................. 6

Line and Circular Source ...................................................................... 7

Line and "Sharp" Point ......................................................................... 7

Triode.................................................................................................... 8

Fluid Mechanism .................................................................................. 8

Appendix: Silver conductive ink Material Safety Data Sheet .......................... 9

Table of Contents

012-04346B

scientific

The PASCO scientific Model PK-9023 Equipotential and

However, permission is granted to non-profit educational

institutions for reproduction of any part of this manual

providing the reproductions are used only for their laborato-

ries 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 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

Please—Feel free to duplicate this manual

subject to the copyright restrictions below.

Should this product have to be returned to PASCO scientific,

for whatever reason, notify PASCO scientific by letter or

phone 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.

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:

1. The carton must be strong enough for the item shipped.

2. Make certain there is at least two inches of packing

material between any point on the apparatus and the

inside walls of the carton.

3. Make certain that the packing material can not shift in

the box, or become compressed, thus letting the

instrument come in contact with the edge of the box.

Equipment Return

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 equip-

ment for warranty repair belongs to the customer. Equip-

ment 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.

scientific

012-04346B

Introduction

10101 Foothills Blvd. • P. O. Box 619011 • Roseville, CA 95661-9011 USA

Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040

scientific

Instructional Manual and

Experiment Guide for the

PASCO scientific Model

PK-9023

FIELD MAPPER

10101 Foothills Blvd. • P. O. Box 619011 • Roseville, CA 95661-9011 USA

Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040

scientific

Instructional Manual and

Experiment Guide for the

PASCO scientific Model

PK-9023

FIELD MAPPER

The PASCO scientific MODEL PK-9023 Field Mapper

consists of two basic elements. The first is a carbon impreg-

nated paper in the resistance range of 5 KΩ to 20 KΩ per

square. This paper forms the conducting medium or space

between the electrodes. The second element is a conductive

ink dispensed from a pen. The ink is produced from silver

particles in a suspension liquid. As the ink dries, the silver

flakes settle on top of each other forming a conductive path,

(or conductive ink electrodes). The resistance of the ink is

between .03 and .05 Ω/cm for a 1 mm wide line.

Because the paper has a finite resistance, a current must flow

through it to produce a potential difference. This current is

supplied by the conductive ink electrodes which causes a

potential drop to occur across the paths. Because of the

large difference between the ink’s resistance and the

resistance of the paper, this potential drop is less than 1% of

that produced across the paper. Therefore, for all practical

purposes the potential drop across the electrodes may be

considered negligible.

Equipment

Equipotential and Field Lines

It would be desirable that the potential measuring instrument

have an infinite impedance. An electrometer such as the

PASCO Model ES-9054B would be optimal, however, a

standard electronic voltmeter such as PASCO's SE-9589

Handheld Digital Multimeter with a 10 MΩ (or higher) input

impedance is sufficient. Since this impedance is at least 100

times greater than that of the paper, the greatest distortion of

the field which can be produced by the voltmeter is approxi-

mately 1%.

The PK-9023 Field Mapper includes:

• 100 sheets of conductive paper with 23 x 30 cm grid

• a silver conductive ink pen for approximately 200 ft of

continuous line

• a corkboard working surface

• 10 push pins for attaching the paper to the board

• 3 wires for connecting the conductive paths

• a circle template for drawing the conductive paths.

• a large plastic tray for storing the paper and other

supplies

• Instruction manual and experiment guide.

The following supplies can be ordered separately

from PASCO scientific

Conductive ink pen Model No. PK-9031B

100 sheets of 23 x 30 cm conductive paper with cm grid

Model No. PK-9025A

100 sheets of 30 x 46 cm conductive paper (without grid)

Model No. PK-9026A

scientific

012-04346B

Equipment Setup

Figure 1

e. A plastic template is included with the PASCO

scientific Field Mapper, for drawing circles. (see

Figure 3) Place the template on the conductive

paper and draw the circles with the conductive ink

pen. (If desired, you may first draw the circle

template with a soft lead pencil and trace over the

pencil line with the ink.)

Figure 3

3. Mount the conductive paper on the corkboard using one

of the metal push pins in each corner.

IMPORTANT:

The silver conductive ink reaches its maximum

conductivity after 20 minutes drying time. For

optimal results plan the timetable for conducting the

experiments and correlate drawing the conductive

ink paths accordingly.

1. Plan and sketch the layout (size, shape and relative

spacing) of the charged paths to be studied on a piece of

scratch paper. These paths can be any two dimensional

shape, such as straight or curved lines, circles, dots,

squares, etc. Since the charged paths will actually be

conductive ink electrodes, they will be referred to as

electrodes.

2. Draw the electrodes on the black paper (see Figure 1).

NOTE: This is the most difficult and crucial part

of the experiment. Follow these steps carefully.

a. Place the conductive paper, printed side up, on a

smooth hard surface. DO NOT attempt to draw the

electrodes while the paper is on the corkboard.

b. Shake the conductive ink pen (with the cap on)

vigorously for 10-20 seconds to disperse any

particle matter suspended in the ink.

c. Remove the cap. Pressing the spring loaded tip

lightly down on a piece of scrap paper while

squeezing the pen barrel firmly starts the ink

flowing. Drawing the pen slowly across the paper

produces a solid line. Drawing speed and exerted

pressure determines the path width. (see Figure 2)

Figure 2

d. Once a satisfactory line is produced on the scrap

paper, draw the electrodes on the black conductive

paper. If the line becomes thin or spotty, draw

over it again. A solid line is essential for good

measurements.

The line will be air dry in 3-5 minutes at room

temperature. However, the medium won’t reach

maximum conductivity until after 20 minutes

drying time.

scientific

012-04346B

4. Connect the electrodes to a battery, DC power supply,

or any other potential source in the 5 to 20 VDC range

using the supplied connecting wires. (see Figure 4) The

potential source should be capable of supplying 25 mA.

(If possible, the potential should be equal to the full

scale reading of the electronic voltmeter used in the

experiment.)

5. To check the electrodes for proper conductivity connect

one voltmeter lead near the push pin on an electrode.

Touch the voltmeter’s second lead to other points on the

same electrode. If the electrode has been properly

drawn, the maximum potential between any two points

on the same electrode will not exceed 1% of the

potential applied between the two electrodes.

NOTE: This test can only be made if the potential

source is connected across the two electrodes.

If the voltage across the same electrode is greater than

1% of the voltage applied between the two electrodes,

then remove the paper from the corkboard and draw

over the electrodes a second time with the conductive

ink.

6. Equipotentials are plotted by connecting one lead of the

voltmeter (the ground) to one of the electrode push pins.

This electrode now becomes the reference. The other

voltmeter lead (the probe) is used to measure the

potential at any point on the paper simply by touching

the probe to the paper at that point.

To map an equipotential, move the probe until the

desired potential is indicated on the voltmeter. Mark the

paper at this point with a soft lead or light-colored lead

pencil. Continue to move the probe, but only in a

direction which maintains the voltmeter at the same

reading. Continue to mark these points. Connecting the

points produces an equipotential line.

7. To plot field gradients (field lines), neither lead of the

voltmeter is connected to an electrode. Instead, the two

leads of the voltmeter will be placed on the conductive

paper side-by-side at a set distance of separation (one

centimeter is a useful separation to use). It is best to tape

the two leads of the voltmeter together for this proce-

dure (see Figure 7). The technique is to use the voltme-

ter leads to find the direction from an electrode that

follows the path of greatest potential difference from

point-to-point.

NOTE: Do Not attempt to make measurements by

placing the leads on the grid marks on the conduc-

tive paper. Touch the voltmeter leads only on the

solid black areas of the paper. It may be necessary

to use a higher voltmeter sensitivity for this

measurement than was used in measuring

equipotentials.

To plot the field lines on the conductive paper, place the

voltmeter lead connected to ground near one of the

dipoles. Place the other voltmeter lead on the paper and

note the voltmeter reading. Now pivot the lead to

several new positions while keeping the ground lead

stationary (see Figure 7). Note the voltmeter readings as

you touch the lead at each new spot on the paper. When

the potential is the highest, draw an arrow on the paper

from the ground lead to the other lead (see Figure 8).

Then move the ground lead to the tip (head) of the

Figure 4

Meter

DC Power

supply

a. Place the terminal of a connecting wire over the

electrode, then stick a metal push pin through its

terminal and the electrode into the corkboard.

Make certain that the pin holds the terminal firmly

to the electrode. (see Figure 5).

Push pin

Connecting

wire

Paper Electrode

Figure 5

NOTE: Check that the surface of the terminal

which touches the electrode is clean. A dirty path

may result in a bad contact.

Connect the other end of the wire to the battery.

THE ELECTRONIC VOLTMETER

Two specifications which a voltmeter must meet in

order to be used with the PASCO scientific Field

Mapper are

• first, an input impedance of 10 MΩ or higher

• second, a full scale range which is equal to or higher

than the potential used across the electrodes.

Any commercial electronic voltmeter, either digital

or analog, that meets these specifications is ad-

equate. The PASCO ES-9054B Electrometer or the

SE-9589 Handheld Digital Multimeter are recom-

mended.

scientific

012-04346B

arrow. Repeat the action of pivoting and touching with

the front lead until the potential reading in a given

direction is highest. Draw a new arrow. Repeat the

action of putting the ground lead at the tip (head) of

each new arrow and finding the direction in which the

potential difference is highest. Eventually , the arrows

drawn in this manner will form a field line. Return to the

dipole and select a new point at which to place the

voltmeter's ground lead. Again probe with the other lead

until the direction of highest potential difference is

found. Draw an arrow from the ground lead to the other

lead, and repeat the process until a new field line is

drawn. Continue selecting new points and drawing field

lines around the original dipole (see Figure 6).

Figure 8

Figure 6 (Example of 3 field lines between unlike dipoles)

Figure 7

Area to probe in order to

find highest potential

difference

Ground lead for

voltmeter

Tape

Pushpin Electrode to voltage

source (battery or

power supply)

Conductive

paper

Dipole Dipole

1st line

2nd line

3rd line

scientific

012-04346B

Experiments

The following are only some suggested experiments in

mapping equipotentials and field gradients using the PASCO

Field Mapper. The true value of the equipment, lies in its

complete flexibility permitting the user to design any system

of charged bodies and then to map the equipotentials and

field gradients.

NOTE: Only power supply connections are shown

in the following schematics. Voltmeter connections

are not shown because they vary depending on

whether equipotentials or field gradients are being

mapped.

Parallel Plate Capacitor

Electrodes

Source

Connecting

wires

Questions

What is the field outside the capacitor plates?

How does the ratio of the plate length (l) versus separation

(d) affect the fringing effect at the edges of the plates?

What redesign of the plates, or perhaps extra electrodes,

could help eliminate the fringing effect?

Point Source and Guard Ring

Questions

What relation can be derived between the distance from the

center of the point source and the equipotential value?

Would this same relation hold if the system were three

dimensional?

What purpose does the large outer ring serve in this experi-

ment?

scientific

012-04346B

Dipoles of Like Charge

Questions

How does the field of this configuration compare with

dipoles of opposite charge? (See experiment “Dipoles of

Opposite Charge”.)

What distortion of the field is produced by the large elec-

trode around the perimeter of the paper?

Dipoles of Opposite Charge

Questions

What is the relation between the direction of a maximum

value field gradient and equipotential line at the same point?

(A geometrical relation is desired.)

What effect does the finite size of the black paper have on

the field?

scientific

012-04346B

Floating Electrode

Before drawing the circular electrode, map the equipotentials

of the two straight electrodes. Draw the circular electrode

and again map the equipotentials.

Questions

How does the circular electrode distort the field?

What is the potential of the circular electrode? Of the area

inside the electrode?

What effect would moving the circular electrode have?

Floating Insulator

Rectangular cut-out

Before cutting the rectangular insulator, map the

equipotentials of the two straight electrodes. Cut out a

rectangular section of the paper and again map the

equipotentials.

Questions

How does the rectangular insulator distort the field?

What effect would moving the rectangular insulator have?

scientific

012-04346B

Line and Circular Source

Draw only the line and point source “a.” Map the

equipotentials. Add circular electrode “b” and again map the

equipotentials. Add circular electrode “c” and again map the

equipotentials.

Questions

How is the spacing of equipotentials affected by the increas-

ing diameter of the circular electrode?

Line and “Sharp” Point

At first, do not draw the two electrodes marked “a.” Map

the equipotentials. Add the electrodes “a” and again map the

equipotentials.

Questions

What effect did adding the extra electrodes have on the

spacing of the equipotentials (field strength) around the

point?

Why did the field strength change even though the radius of

the point did not change?

scientific

012-04346B

Triode

Equipment needed but not supplied: 5K Potentiometer

Potentiometer

Use a 5 K potentiometer to provide three potentials. Con-

nect the three short electrodes with wires “a.” Do not let

these wires touch the black paper except at the conductive

ink electrodes.

Questions

How is the field in the area between the short electrodes

affected by the potential between the short electrodes and the

closer, long electrode?

Could this paper model of a triode act as an amplifying

device? If not, why not?

Fluid Mechanics Experiments

Cut-out shape

The PASCO Field Mapper can also be used to examine fluid

flow. In many fluid systems the velocity potential satisfies

the Laplace equations (so does the electromagnetic poten-

tial). Consequently, there is a direct analogy between fluid

flow and electric fields. In particular, the velocity potential

of an incompressible fluid where the flow is both steady and

not rotational satisfies the Laplace equation. A steady flow

of water is a good approximately of this type of flow. Now

the flow is generated by “sources” which supply fluid and

“sinks” which absorb fluid. We are interested in the

“streamlines” which can be thought of as lines traced out by

a particular particle in the fluid. The streamlines begin at the

sources and end at the sinks.

Turning to the Field Mapper, we need to draw electrodes in

the shape of the sources and sinks in the fluid flow to be

examined. Then the electric field lines which we plot

coincide with the streamlines in the fluid flow. (Remember

that the electric field lines are perpendicular to the equipo-

tential lines.) If there is some fixed obstruction in the fluid

glow, we can represent it by cutting the same shape from the

conductive paper. The schematic drawing shows a fluid

flow which is analogous to the flow in a section of pipe

(with frictionless walls). This source is a straight line at the

left, the sink is a straight line at the right. The tear-drop

shaped section cut out of the middle is some obstruction.

The field lines are the corresponding streamlines.

To use the Field Mapper to examine fluid flows, follow these

steps.

1. Make sure that the fluid is incompressible and the flow

is not rotational and steady.

2. Draw electrodes on the conductive paper in the same

shape and position as the sources and sinks in the flow.

3. Cut out sections of the conductive paper in the same

shape and position as the obstructions in the fluid.

4. Connect a battery between the sources and sinks. All

sources should be connected to the same side of the

battery. All sinks should be connected to the opposite

side.

5. Plot the equipotentials and draw lines perpendicular to

these. You can also pick any point and determine the

direction of the maximum field gradient. This is the

direction of the streamlines at that point.

scientific

012-04346B

Notes

scientific

012-04346B

Appendix

scientific

012-04346B

Technical Support

Feedback

If you have any comments about the product or

manual, please let us know. If you have any sugges-

tions on alternate experiments or find a problem in the

manual, please tell us. PASCO appreciates any

customer feedback. 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: techsupp@PASCO.com

web: www.pasco.com

Contacting Technical Support

Before you call the PASCO Technical Support staff,

it would be helpful to prepare the following infor-

mation:

➤ 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 can’t call PASCO right

away, you won’t lose valuable data.);

-If possible, have the apparatus within reach

when calling to facilitate description of indi-

vidual 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 ques-

tions.

Pasco Specialty And Mfg Equipopotential Field Mapper Pk 9023 Users Manual 0

Navigation menu

Versions of this User Manual:

Views

Navigation