PASCO Specialty & Mfg. PK-9023 User's Manual
Contents
1. 1st line 04 4 4 4 4 0 Dipole Dipole 2nd line a EK 7 oq lt lt lt lt Oo a 7 xk a O4 q lt 40 x Pd o e 4 3rd line Figure 6 Example of 3 field lines between unlike dipoles Area to probe in order to find highest potential difference Conductive paper N Ground lead for voltmeter Electrode to voltage source battery or power supply Figure 8 4 PASCO 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 PD DC AE i Source M Connecting wires Electrodes 7 Questions What is the field outside the capacitor plates How does the ratio of the plate length 1 versus separation d affect the fringing effect at the edges of the plates What redesign of the plates or perhaps extra electrodes could help eliminate2. Instruction Manual and 012 04346B Experiment Guide for a the PASCO scientific Model PK 9023 EQUIPOTENTIAL AND FIELD MAPPER Copyright October 1990 better better 4 0 10101 Foothills Blvd Roseville CA 95747 7100 mm S c ent f c Phone 916 786 3800 FAX 916 786 8905 www pasco com 012 04346B Table of Contents Section Page Copyright Warranty and Equipment Rein usa ae 11 Introduction sonnin ap e aa a a aa eaten ees 1 e ge Un IUE 1 Equipment Sep une M n 2 Experiments Parallel Plate Capacitor ea kt 4 Point Source and Guard Ring use teca pe abeo uia ie bucpiae 4 Dipoles of Opposite Charela 8 Dipoles of Like Charpe nei 5 Floating Bleetr de D m 6 Floating Insulator ee ee 6 Lima and Circular Saure nen J Lime and Sharp Pollari 7 o ceeded ET 8 Fluid Mechanist ra 8 Appendix Silver conductive ink Material Safety Data Sheet 9 i PASCO scientific 012 04346B Copyright and Warranty Please Feel free to duplicate this manual subject to the copyright restrictions below Copyright Notice The PASCO scientific Model PK 9023 Equipotential and Field Mapper manual is copyrighted and all rights reserved However permission is granted to non profit educational institutions for reproduction of any part of this manual providing the reproductions are used only for thei
3. Model No PK 9025A 100 sheets of 30 x 46 cm conductive paper without grid Model No PK 9026A 012 04346B Equipment Setup 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 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 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 wid
4. 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 PASCO scientific 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 represe
5. from the corkboard and draw over the electrodes a second time with the conductive ink 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 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
6. 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 PASCO scientific 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 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 PASCO scientific 012 04346B Floating Electrode O 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 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 equi
7. EASURES Appropriate hygenic practices Throughly wash hands after use Avoid skin contact Personal protective equipment Safety glasses and gloves recommended Work practices Follow good laboratory practices Handling and storage precautions Store in sealed containers in a cool place away from open flames Engineering controls Area of use should be well ventilated 12 PASCO scientific 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 gt 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 gt If your p
8. G Silver Conductive Material Health hazard 1 Slight Flammabilty hazard 2 Moderate Reactivity hazard 0 Minimal Appearance and odor Silver color organic ester odor II HAZARDOUS INGREDIENTS amp EXPOSURE LIMITS This material is a silver pigmented paint and contains organic ester solvents Threshold limits of 100 ppm or less is recommended HI TYPICAL PHYSICAL amp CHEMICAL CHARACTERISTICS Boiling Point 125 150C Solubility in water v si sol Vapor 10 20 mm 20 C Specific gravity 1 65 Vapor Density 2 2 pH N A volatile vol approximately 50 Evaporation rate 0 85 Freezing Point Below 40 F Butyl Acetate 1 0 IV FIRE EXPLOSION amp REACTIVITY HAZARD DATA Flash point 37 closed cap Autoignition temperature Not listed Extinguishing media Carbon dioxide or foam type Special fire fighting procedures None Unusual fire amp explosion hazards None Stability considerations Stable Incompatability with Stong oxidizers such as acids Hazardous decompositoin products None Hazardous products of composition None Hazardous polymerization Will not occur We cannot anticipate all conditions under which this information and our products or the products of other manufactur ers in combination with our products may be used We accept no responsibility for results obtained by the application of this information or the safety and suitability of our products either alone or in a combinat
9. e maximum potential between any two points on the same electrode will not exceed 1 of the potential applied between the two electrodes DC Power supply NOTE This test can only be made if the potential source is connected across the two electrodes Figure 4 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 Connecting wire Push pin 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 e first an input impedance of 10 MQ 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 PASCO scientific Tf the voltage across the same electrode is greater than 1 of the voltage applied between the two electrodes then remove the paper
10. eturning 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 PASCO scientific 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 012 04346B Introduction 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 KQ to 20 KQ 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 Q 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 dif
11. ference 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 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 MQ 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 Equipment PASCO scientific 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 nstruction 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
12. ion with other products Users are advised to make their own tests to determine the safety and suitability of each such product or product combination for their own purposes Unless otherwise agreed in writing we sell the products without warranty Buyers and users assume all responsibility and liability for loss or damage arising from the handling and use of our products whether used alone or in combination with other products PASCO scientific 11 012 04346B Planned Products Issue Date 1 1 87 2 p 0 0 303 Potrero Street Suite 53 Santa Cruz CA 95060 USA Tel 408 459 8088 Fax 408 459 0426 Page 2 of 2 V HEALTH HAZARD DATA ian mptom Eyes May cause irritation Skin Prolonged exposure causes dermatitis possible rash Ingestion Unknown EMERGENCY i Eyes Wash immediately with warm water Skin Wash with soap and warm water Inhalation Remove to fresh air ingestion Possible POISON in high doses Immediately call Physician Medical conditions generally recognized as being aggravated exposure In high concentrations will cause possible lightheadedness narcosis and respiratory irritation Primary routes of entry Inhalation and skin contact VI SPILL amp LEAK PROCEDURES TEPS TO B NIE MATERI LEASED OR SP Soak up with absorbant such as vermiculite Place in sealed metal containers Waste Disposal Method Place in sealed metal cans and retum to supplier for disposal VII APPLICABLE CONTROL M
13. nt 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 1s 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 012 04346B Notes 10 PASCO scientific 012 04346B Appendix MATERIAL SAFETY DATA SHEET Planned Products 2200 303 Potrero Street Suite 53 Santa Cruz CA 95060 USA Tel 408 459 8088 Date 1 1 87 Fax 408 459 0426 Page 1 of 2 I PRODUCT IDENTIFICATION 2200 CONDUCTOR CLASS RAIIN
14. potentials Questions How does the rectangular insulator distort the field What is the potential of the circular electrode Of the area inside the electrode What effect would moving the rectangular insulator have What effect would moving the circular electrode have PASCO scientific 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 012 04346B 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 PASCO 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
15. r 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 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 Equipment Return 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 r
16. roblem 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
17. th see 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 3 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 Mount the conductive paper on the corkboard using one of the metal push pins in each corner PASCO 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 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 th
18. 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 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 012 04346B 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
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