PASCO Specialty & Mfg. SE-9639 User's Manual
Contents
1. Ah h ho ho x 100 Questions 1 Should you use the positions of the peaks or of the valleys to determine the excitation energy Or both Explain 2 Why are the peaks and valleys smeared out rather than sharp 3 How precisely can you determine the peak valley position Explain and justify your estimates 4 How would molecular contaminants in the tube affect your results PASC Qi 012 14264A 13 SE 9639 Franck Hertz Experiment Experiment Procedure 2 Using a PASCO Interface and Data Acguisition Software Current Amplifier Interface Port Argon Tube Power Supply ak Enclosure Analog Analog InputA Input B EN B M i FRANCK HERTZ TUBE Eht 9 850 Universal Power Supplv II 3 A Interface i E 8 pin DIN Extension Cable Items Needed S 850 Universal Interface Ul 5000 PASCO Capstone Software UI 5400 See the PASCO web site at www pasco com for more information Hardware Setup Connect Cables and Cords Note Before connecting any cords or cables be sure that all power switches on the Interface Power Supplies and Current Amplifier are in the OFF position and all volt age controls are turned fully counterclockwise 1 Connect all the cables and cords between the argon tube enclosure and the power supplies and current amplifier 2 Connect one 8 pin DIN Extension Cable UI 5218 from the INTERFACE port on the DC Current Amplifier to ANA LOG INPUT A on the Univer2. 6 892 x 10 74 Jes which is 6 892 6 604 0 29 x 104 Jes Therefore the experimental value for h is 6 6 0 3 x 107 Jes So the answer is accurate to 0 to as many significant figures as we have but the precision is only 4 5 Questions 1 Should you use the positions of the peaks or of the valleys to determine the excitation energy Or both Explain Use both The average of the accelerating voltages matching peak positions and the valley positions is the voltage for the approximate excitation energy e Up 2 Why are the peaks and valleys smeared out rather than sharp The shape of the peaks and valleys in the curve is affected by the fact that there is a potential drop of 1 5 V at the cathode which is the source of the electrons The cathode potential causes the peaks and valleys to occur over a space of 1 5 V rather than at a sharp point 3 How precisely can you determine the peak valley position Explain and justify your estimates Note that the current fluctuations in the vicinity of the peaks the width of the peaks the steepness of the drop off or rise and background height and shape all may play a role in this 4 How would molecular contaminants in the tube affect your results The molecular contaminant in the tube has a different first excitation potential Vy so that the measurement of argon atom s first excitation potential would be affected Appendix C Technical Support For assistance with the equipment o
3. 4 5 0 V DC 4 5 30 V DC ripple lt 1 Two ranges lt 10mA 4 5 Digit Display Tunable DC Constant Voltage 0 12 V DC I lt 1A ripple lt 1 3 5 Digit Display Power Supply Il 0 100 V DC 0 200 V DC ripple lt 1 Two ranges lt 30mA 3 5 Digit Display DC Current Amplifier Current range 10 107 A in six ranges 3 5 Digit Display Zero drift lt 1 of full range reading in 30 minutes at the range of 1019 A after a 20 minute warm up Argon Tube Filling gas argon Filament voltage lt 6 3 V DC Accelerating voltage lt 100 V DC Wave crest or trough number 6 Life span gt 2000 hours Franck Hertz Experiment Appendix B Teacher s Notes Appendix B Teacher s Notes Sample Data 1 Manual Measurements Filament voltage V 3 55 V V61kK 1 5V VG2A 11 0 V Table 1 Accelerating Voltage and Tube Current va 1 fe 3 4 s e 7 e a pera oe CE C CEO C COR LN pore SS AIR IA AA IA IA ASIA Ap memo ju ejn ele LACA TEKA CIA SN A A eee aje jee TEKA Vem M ee Me ee fe ea TYM K p fe a a e oe gt A TS A ESE SEALS eee a meho FIA E A A A A A A AO TMK KKK KK KM MN LL ee e A A NE ery ar we ee ew a oe ow vam a o e IC pern m m a IA PASCOS ET SE 9639 Franck Hertz Experiment Franck Hertz Curve for Argon l l f M M id 10 20 Ms 40 50 60 70 Vazk V 2000 1800 1600 1400 1200 E etl AAN J la x10 A 1000 600
4. Jes 4 Calculate the percent difference between the experimental value and the accepted value h 6 626 x 10 J es 5 Estimate the uncertainty in the experimental value of Planck s Constant using the uncertainty in the voltage difference Franck Hertz Experiment Analysis m Franck Hertz2cap PASCO Cop GRE y File Edit Workbook Display Journal Help Bev BBE a o B Introduction Theory Theory 2 Setup Setup 2 Procedure Recording Analysis x Hardware Setup Accelerating Voltage Acc Voltage V Run 9 85 31V Diff between Peaks diff 1 Peak Voltage V Difference Difference Peak Voltag ir hotwoca beween Tr v e roughs oughs wi m v v lt s I o m x 2 E o E 5 o E o i 5 U qu w Properties if Choose Interface Add Sensor Instrument Mean Std Dev 40 Voltage V Controls x h Delete Last Run 00 00 00 Voltage Sensor w 20 00 Hz gt PASCO T SE 9639 Franck Hertz Experiment Appendix A General Specifications pen Relative humidity Noncondensing lt 10 C 90 from 10 C to 30 C 75 from 30 C to 40 C Pollution degree Certifications CE Safety compliance IEC EN 61010 1 Overvoltage category Degree of protections Normal energy protection Item Description Tunable DC Constant Voltage 0 6 3 V DC lt 1A ripple lt 1 3 5 Digit Display Power Supply
5. for electrons passing through mercury vapor and a corresponding emission at the ultraviolet line A 254 nm of mer cury As it is not possible to observe the light emission directly demonstrating this phenomenon requires extensive and cumbersome experiment apparatus They performed this experiment that has become one of the classic demonstrations of the quantization of atomic energy levels They were awarded the Nobel Prize for this work in 1925 In this experiment we will repeat Franck and Hertz s energy loss observations using argon and try to interpret the data in the context of modern atomic physics We will not attempt the spectroscopic measurements since the emissions are weak and in the extreme ultraviolet portion of the spectrum Principle of the Experiment The Franck Hertz tube is an evacuated glass cylinder with four electrodes a tetrode which contains argon The four electrodes are an indirectly heated oxide coated cathode as an electron source two grids G1 and G and a plate A which serves as an electron collector anode A Grid 1 G1 is positive with respect to the cathode K about 1 5 V A variable potential difference is applied between the cathode and Grid 2 G so that electrons emitted from the cathode can be accelerated to a range of electron energies The distance between the cathode and the anode is large compared with the mean free path length in the argon in order to ensure a high collision probability O
6. in the vicinity of the peaks the width of the peaks the steepness of the drop off or rise and background height and shape all may play a role in this 4 How would molecular contaminants in the tube affect your results The molecular contaminant in the tube has a different first excitation potential Vy so that the measurement of argon atom s first excitation potential would be affected Sample Data 2 Using a PASCO Interface Filament voltage V 3 55 V Vo1 K 1 5V VG2A 11 0V 100 Y Run 9 All AV 20 v 2 11 08 i 3 11 34 gt 60 4 11 88 g 5 11 44 E 4 6 12 09 6 Ww 7 11 13 8 11 94 Mean 11 44 0 Std Dev 0 50 0 20 40 60 30 Acc Voltage V Peak Voltage Diff between Peaks Trough Voltage Difference between Troughs v v v Vv 1 22 11 10 62 26 51 11 44 2 32 73 11 08 37 95 12 09 3 43 81 11 54 50 04 11 13 4 35 15 11 88 61 17 11 94 3 67 03 73 11 Mean 44 17 11 23 49 76 11 65 Std Dev 17 75 0 55 16 41 0 44 PASCO r SE 9639 Franck Hertz Experiment Analysis Obtain the value of argon atom s first excitation potential Vy 11 44 V Calculate the value of Planck s Constant h where e 1 602 x 10 C A 108 1 nm and c 3 x 10 m s Based on the data Planck s Constant h 6 604 x 10 34 Jes Calculate the percent difference between the experimental value and the accepted value hp 6 626 x 10 J es Ah h ho hg x 100 0 3 Using Vp 11 44 0 50 V 11 94 V gives h
7. zero press the SIGNAL button in to CALIBRATION Adjust NOTE It is very important to the CURRENT CALIBRATION knob until the current reads zero Press the SIGNAL allow the argon tube and button to MEASURE apparatus to warm up for 15 minutes prior to making any 4 On the DC Constant Voltage Power Supply I set the Voltage Range switch to 4 5 measurements 30 V On Power Supply II set the Voltage Range switch to 0 100 V 5 On Power Supply I rotate the 0 6 3 V adjust knob until the voltmeter reads 3 5 V This sets Vg 3 5 V Filament Volt age Note The Argon Tube Enclosure may have a different suggested filament voltage If so use it instead of 3 5 V 6 On Power Supply I rotate the 4 5 30 V adjust knob until the voltmeter reads 1 5 V This sets VG1g 1 5 V the volt age between the first grid and the cathode 7 Rotate the 0 12 V adjust knob until the voltmeter reads 10 0 V to set Vga 10 0 V Retarding voltage 8 Rotate the 0 100 V adjust knob until the voltmeter reads 0 V This sets Vg2zx 0 V Accelerating voltage 9 Remember allow the argon tube and the apparatus to warm up for 15 minutes 10 When you have finished the above steps check that Vy 3 5 V Filament voltage VG1k 1 5 V the voltage between the first grid and cathode and Vg24 10 0 V voltage between the second grid and anode retarding voltage If so the equipment is ready to do the experiment Note These are sugges
8. 1 Tunable DC Constant Voltage Power Supply SE 6615 1 2 Tunable DC Constant Voltage Power Supply II SE 9644 1 3 DC Current Amplifier SE 6621 1 1 4 Argon Tube Enclosure with Argon Tube SE 9650 MA 5 Connecting cable 850 mm red EM 9740 Setof 5 6 Connecting cable 850 mm black EM 9745 Set of 5 7 Power Cord LE 8 BNC Cable 9 8 pin DIN Extension Cable Ul 5218 SE 9639 Franck Hertz Experiment Recommended Items 850 Universal Interface Ul 5000 PASCO Capstone Software Ul 5400 Limited Warranty and Limitation of Liability This Brolight product is free from defects in material and workmanship for one year from the date of purchase This warranty does not cover fuses or damage from accident neglect misuse alteration contamination or abnormal conditions of operation or handling Resellers are not authorized to extend any other warranty on Brolight s behalf To obtain service during the war ranty period return the unit to point of purchase with a description of the problem THIS WARRANTY IS YOUR ONLY REMEDY NO OTHER WARRANTIES SUCH AS FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSED OR IMPLIED BROLIGHT IS NOT LIABLE FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAM AGES OR LOSSES ARISING FROM ANY CAUSE OR THEORY Since some states or countries do not allow the exclusion or limitation of an implied warranty or of incidental or consequential damages this limitation of liability may not apply to you Safety I
9. 400 Table 2 Peak and Valley Voltages positions a s a 06 a wm e E CH E LO positions nemon w AA Analysis Obtain the value of argon atom s first excitation potential V9 Vo peak Vg V1 5 11 3 V Vo valley V V 5 12 0 V Therefore Vo 11 65 V Calculate the value of Planck s Constant h Vo h eno where e 1 602 x 10 C 108 1 nm and ec 3 x 108 m s Based on the data Planck s Constant h 6 725 x 1034 Jes Calculate the percent difference between the experimental value and the accepted value h 6 626 x 10 Jes Ah h ho hg x 100 1 5 Questions 1 Should you use the positions of the peaks or of the valleys to determine the excitation energy Or both Explain Franck Hertz Experiment Sample Data 2 Using a PASCO Interface Use both The average of the accelerating voltages matching peak positions and the valley positions is the voltage for the approximate excitation energy e Up 2 Why are the peaks and valleys smeared out rather than sharp The shape of the peaks and valleys in the curve 1s affected by the fact that there is a potential drop of 1 5 V at the cathode which is the source of the electrons The cathode potential causes the peaks and valleys to occur over a space of 1 5 V rather than at a sharp point 3 How precisely can you determine the peak valley position Explain and justify your estimates Note that the current fluctuations
10. Instruction Manual 012 14264A Franck Hertz Experiment Model SE 9639 Brolight Technology Co Ltd O f A To O 1 916 786 3800 800 772 8700 support pasco com www pasco com Table of Contents Equipment List 1 Limited Warranty and Limitation of Liability 2 Safety Information 2 Installation and Maintenance 3 Introduction 5 Principle of the Experiment 5 Experiment Procedure 1 11 Experiment Procedure 2 14 Appendix A General Specifications 18 Appendix B Teacher s Notes 19 Appendix C Technical Support Copyright Warranty 23 Product End of Life Disposal Instructions 23 CTK i Instruction Manual 012 14264A Franck Hertz Experiment SE 9639 Select Select MEASURE l CURRENT Adjust RANGES CURRENT CALIBRATION Select 45V 0Vv L 4 5 V 30 V Select Adjust Adjust A o 100v 97 100V 45V 0V Adjust and and 4 5 V 30 V Equipment List Included Equipment Model Quantity
11. Note Replace the cables and power cords with the same type 012 14264A PASC O Franck Hertz Experiment Tunable DC Constant Voltage Power Supply Tunable DC Constant Voltage Power Supply Voltmeter Voltage Range Voltmeter Switch solih Power pn Switch V fo oN 4 5V 0V PASCO 850 ey 0 63V 4 5V 30V Universal LS DR Interface Ports f g max O Imax LOMA O Voltage Output BEM 5001 Adjust 0 6 3V Adjust 4 5 0V 4 5 30 V Voltmeter Displays voltage across the argon tube Voltage Range Switch Sets the voltage range as 4 5 0 V Ll or 4 5 30 V G Power Switch Turns the power to the instrument ON or OFF Voltage Adjust Sets the voltage across the argon tube Output Output power Data Interface Connect to the analog channels of the PASCO 850 Universal Interface Tunable DC Constant Voltage Power Supply II Voltmeter Voltage Range Voltmeter Switch TUNABLE DC Constant Voltage POWER SUPPLY Brolight A V Power Switch V f ane 0 100V PASCO 850 ye 0 200V Universal L e Interface Ports i max O max 30MA O INTERFACE Voltage Outpu BEM 5002 Voltmeter Displays voltage across the argon tube Voltage Range Switch Sets the voltage range as 0 to 100 V Ll or 0 to 200 V 2 for the accelerating volt age Power Switch Turns the power to the instrument ON or OFF Voltage Adjust Sets the voltage for both voltage ranges SE 9639 Franck Hert
12. e e Pull up on the elastic pressing spring and rotate it off the argon tube e Gently pull out the argon tube e Then install a new tube and replace the elastic pressing spring e Finally close the case and replace the two small screws e Note The tube is a thin walled evacuated glass bulb Handle with care Do not expose the tube to mechanical stress or strain Argon Tube Specifications Be Wave crest or trough number ie Note Replace the argon tube with the same type Model SE 9645 Franck Hertz Ar Tube Fuse Replacement WARNING The fuse is inside a tray Open the cover to remove the fuse To reduce the risk of electric shock or damage to the instrument turn the power switch OFF and disconnect the power cord before replacing a fuse e Disconnect the power cord from the instrument e Open the fuse cover and remove the fuse The fuse is inside a tray Use a small Fuse Cover Tray screwdriver or other tool to pry the tray open e Replace the fuse s Use the same type of fuse 250 V T2A oo e Reconnect the power cord and turn on the instrument Pry e Ifthe problem persists contact Brolight Corporation for service th Note Replace the burned fuses with new fuses of the same type One spare fuse is included Franck Hertz Experiment Introduction Introduction In 1914 James Franck and Gustav Hertz discovered in the course of their investigations an energy loss in distinct steps
13. e 30 V AC rms 42 V peak or 60 V DC Such voltages pose a shock hazard e To avoid electric shock do not touch any bare conductor with hand or skin e Adhere to local and national safety codes Individual protective equipment must be used to prevent shock and arc blast injury where hazardous live conductors are exposed 2212264 TN Franck Hertz Experiment Electrical Symbols e Special note If a dangerous voltage is applied to an input terminal then the same voltage may occur at all other terminals Electrical Symbols Cuy Alternating Current _ Direct Current N Caution risk of danger refer to the operating manual before use Caution possibility of electric shock Earth ground Terminal Protective Conductor Terminal L Chassis Ground Conforms to European Union directives M WEEE waste electric and electronic eguipment gt Off Power L In position of a bi stable push control Out position of a bi stable push control Installation and Maintenance WARNING A N To reduce the risk of electric shock or damage to the instrument turn the power switch off and disconnect the power cord before replacing a tube PASCOS ee SE 9639 Franck Hertz Experiment Replace the Argon Tube e Use a flat blade screwdriver to remove the two small screws that hold the back plate onto the argon tube enclosure e Use a small flat blade screwdriver to pry the back panel off of the enclosur
14. e excited atom Filament Figure 1 1 Franck Hertz tube Figure 2 displays a typical measurement of the anode current I as a function of the accelerating voltage As soon as Vx gt VGaa the current increases with rising Vx Notice that the current sharply decreases for a voltage U and then increases up to U and then this pattern recurs The interpretation of these observations is suc cessful with the following assumptions e Having reached energy of about e Uo electrons can transmit their kinetic energy to a discrete excitement state of the argon atoms e As aresult of the inelastic collision they pass the braking volt OT Uz Us Us Us Us Uczkw age e If their energy is twice the required value or 2 e Ug they can Up Up 1 1 is collide two times inelastically and similarly for higher volt ages Figure 1 2 Anode current curve e Asa matter of fact a strong line can be found for emission and absorption corresponding to an energy of e Up the exci tation energy of argon in the optical spectrum 108 1 nm In figure 2 the resonance voltage is denoted by Up er Uy hf hc OT where e is the charge on an electron h is Planck s Constant and c is the speed of light 6 aaa TN Franck Hertz Experiment Connect Cables and Cords Connect Cables and Cords 110 120 V or 220 240 V Please make sure that you select the right setting according to your AC voltage level Note Before connec
15. ge Vc for which the current reaches a local maximum and begins to drop on further increase of the accelerating voltage Take a few data points V G2 K I around these peak positions and record them in Table 1 2 Try to identify the valley positions 1 e watch for those values of the accelerating voltage Vg2x for which the current reaches a local minimum and begins to rise on further increase of the accelerating voltage Take a few data points VG2k IA around these valley positions and record them in Table 1 2 3 Take sufficiently many voltage values so as to allow you to determine the positions of the peaks and valleys Table 1 1 Accelerating Voltage and Tube Current Mow O AO AOS O IO II IO IS acota LL fo Yoo pop Table 1 2 Peak and Valley Voltages Ve VI V positions a r100 A meat NN NN D ee O o positions nea L LOL Analysis 1 Plot the graphs of Current y axis versus Voltage x axis Franck Hertz Experiment Ouestions 2 Find the peak or valley positions which match the accelerating voltages labeled V1 V2 V3 V4 V5 and V6 3 Obtain the value of argon atom s first excitation potential Vo w V V V3 V V4 V3 V5 Vy V Vs o 4 Calculate the value of Planck s Constant h where e 1 602 x 107 C A 108 1 nm and e 3 x 108 m s 5 Calculate the percent difference between the experimental value and the accepted value hy 6 626 x 10 J es
16. icates that this product must not be disposed of in a standard waste container PASCO ey
17. ions before they reach the anode After the collision by the time they reach the grid they have obtained enough energy to overcome the retarding voltage and will reach the collector plate Thus I will increase Again when a certain voltage V is reached we note that I drops This means that the electrons have obtained enough energy to have two inelastic collisions before reach ing the grid G5 but have not had enough remaining energy to overcome the retarding voltage Increasing the voltage again I starts upward until a third value V3 of the voltage is reached when I drops This corresponds to the elec trons having three inelastic collisions before reaching the anode and so on The interesting fact is that V3 V gt equals V gt Vy ete which shows that the argon atom has definite excitation levels and will absorb energy only in quantized amounts PASC Oi 012 14264A SE 9639 Franck Hertz Experiment When an electron has an inelastic collision with an argon atom the kinetic energy lost to the atom causes one of the outer orbital electrons to be pushed up to the next higher energy level This excited electron will within a very short time fall back into the ground state level emitting energy in the form of photons The original bombarding electron is again accelerated toward the grid anode Therefore the excitation energy can be measured in two ways by the method outlined above or by spectral analysis of the radiation emitted by th
18. n the other hand the separation between G and the collector electrode A is small A small constant negative potential Ugo retarding potential is applied between G and the collector plate A 1 e A is less positive than G3 The resulting electric field between G3 and collector electrode A opposes the motion of electrons to the collector electrode so that elec trons which have kinetic energy less than e Ug24 at Grid 2 cannot reach the collector plate A As will be shown later this retarding voltage helps to differentiate the electrons having inelastic collisions from those that don t A sensitive current amplifier is connected to the collector electrode so that the current due to the electrons reaching the collector plate may be measured As the accelerating voltage is increased the following is expected to happen Up to a certain voltage say Vy the plate current I will increase as more electrons reach the plate When the voltage V is reached it is noted that the plate current I takes a sudden drop This is due to the fact that the electrons just in front of the grid G have gained enough energy to collide inelastically with the argon atoms Having lost energy to the argon atom they do not have sufficient energy to over come the retarding voltage between G and collector electrode A This causes a decrease in the plate current I Now as the voltage is again increased the electrons obtain the energy necessary for inelastic collis
19. nformation e Do not clean the equipment with a wet cloth e Before use verify that the apparatus is not damaged e Do not defeat power cord safety ground feature e Plug into a grounded earthed outlet Do not use the product in any manner that is not specified by the manufacturer e Do not install substitute parts or perform any unauthorized modification to the product e Line and Current Protection Fuses For continued protection against fire replace the line fuse and the current protection fuse only with fuses of the specified type and rating e Main Power and Test Input Disconnect Unplug instrument from wall outlet remove power cord and remove all probes from all terminals before servicing Only qualified service trained personnel should remove the cover from the instrument e Do not use the equipment if it is damaged Before you use the equipment inspect the case Pay particular attention to the insulation surrounding the connectors e Do not use the equipment if it operates abnormally Protection may be impaired e When in doubt have the equipment serviced e Do not operate the equipment where explosive gas vapor or dust is present Don t use it under wet conditions e Do not apply more than the rated voltage as marked on the apparatus between terminals or between any terminal and earth ground e When servicing the equipment use only specified replacement parts e Use caution when working with voltages abov
20. of V In the fourth column of the table create a calculation IPASCOS O SE 9639 Franck Hertz Experiment e Diff between Peaks diff 1 Trough Voltage V with units of V This calculation calculates the voltage difference between adjacent current troughs 9 In the table turn on the mean and standard deviation Recording Data 1 Make sure the accelerating voltage VG 1s zero 2 After the filament has warmed up for about 15 minutes click Record and slowly increase the accelerating voltage take about two minutes Do not exceed 85 V CAUTION While you are increasing the voltage if you see the current suddenly increase immediately return the voltage to zero and decrease the filament voltage slightly Wait for a few minutes for it to cool and repeat the recording Analysis 1 Using the coordinates tool on the graph find the voltage of each of the peaks and troughs and record them in the table in the Peak Voltage and Trough Voltage columns respectively 2 The voltage differences between adjacent peaks and the voltage differences between adjacent troughs will be calculated automatically in the table Record the mean and standard deviations for the differences The standard deviations give the uncertainties in the difference measurements 3 Use the mean voltage difference Vy to calculate the value of Planck s Constant A Vo h ed where e 1 602 x 107 C A 108 1 nm and c 3 x 108 m s The answer will be in
21. r any other PASCO products contact PASCO as follows Address PASCO scientific 10101 Foothills Blvd Roseville CA 95747 7100 Phone 1 916 4626 8384 worldwide 877 373 0300 U S Web WWW pasco com Email support Apasco com Franck Hertz Experiment Appendix D Product End of Life Copyright Notice The PASCO scientific manual is copyrighted and all rights reserved However permission is granted to non profit educational institutions for reproduction of any part of the 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 Warranty For a description of the product warranty see the PASCO catalog Appendix D Product End of Life Product End of Life Disposal Instructions This electronic product is subject to disposal and recycling regulations that vary by country and region It is your responsibility to recycle your electronic equipment per your local environmental laws and regulations to ensure that it will be recycled in a manner that protects human health and the environment To find out where you can drop off your waste equipment for recycling please contact your local waste recycle disposal service or the place where you purchased the product The European Union WEEE Waste Electronic and Electrical Eguipment symbol above and on the product or on its packag ing ind
22. s on the Argon Tube Enclosure and connect the negative terminal of the power supply to the ter minal labeled K black sockets on the enclosure On Power Supply I SE 6615 connect the positive terminal of the 4 5 30 V DC output on the power supply to the grid like electrode labeled G1 on the Argon Tube Enclosure and connect the negative terminal of the power supply to the terminal labeled K black sockets on the enclosure On Power Supply I connect the positive terminal of the 0 6 3 V DC output on the power supply to the red socket of the port labeled FILAMENT on the Argon Tube enclosure and connect the negative terminal of the power supply to the black socket of the FILAMENT port Note Before connecting the power cords please check that the setting for the input voltage range 110 120 V or 220 240 V matches the local AC voltage For the two power supplies and the current amplifier connect a power cord between the port on the back labeled AC POWER CORD and an appropriate electrical outlet DANGER High Voltage is applied to the Argon Tube Avoid contact with any part of the body Only use safety equipment leads shrouded patch cords for connections Make sure that the power supplies and current amplifier are OFF before making the connections Make sure that the power supplies and current amplifier are OFF before installing or replacing the argon tube in the Argon Tube Enclosure
23. s 0 V This sets Vg2zx 0 V Accelerating voltage Remember allow the argon tube and the apparatus to warm up for 15 minutes When you have finished the above steps check that Vy 3 5 V Filament voltage Ve1k 1 5 V the voltage between the first grid and cathode and Vg24 10 0 V voltage between the second grid and anode retarding voltage If so the equipment is ready for the experiment Note These are suggested settings for the experiment but other values could be tried You can do the experiment by parameters that are marked on the Argon Tube Enclosure Software Setup l 2 Start the PASCO Capstone software The current is a very small number so to make the current to appear as a number between zero and 100 on the graph cre ate a calculation Electron Current Current Ch A A x 10 10 with units of x 104 10 A Create a graph of Electron Current vs Voltage Create a digits display of the Voltage This will clearly show you the accelerating voltage so you can monitor it to make sure that you do not exceed 85 V Create a table and create Run tracked User Entered Data called Peak Voltage with units of V In the second column of the table create a calculation Diff between Peaks diff 1 Peak Voltage V with units of V This calculation calculates the voltage difference between adjacent current peaks Add a column and create Run tracked User Entered Data called Trough Voltage with units
24. sal Interface UI 5100 Franck Hertz Experiment Software Setup 10 11 12 Connect a second 8 pin DIN Extension Cable from the 0 100V 0 200V INTERFACE port on Power Supply II to ANALOG INPUT B on the Universal Interface Turn ON the power for the Universal Interface the power supplies and the current amplifier On the DC Current Amplifier turn the CURRENT RANGES switch to 107 A To set the current amplifier to zero press the SIGNAL button in to CALIBRATION Adjust the CURRENT CALIBRATION knob until the current reads zero Press the SIGNAL NOTE l is very important to button to MEASURE allow the argon tube and apparatus to warm up for 15 On the DC Constant Voltage Power Supply I set the Voltage Range switch to 4 5 minutes prior to making any 30 V On Power Supply II set the Voltage Range switch to 0 100 V 11 measurements On Power Supply I rotate the 0 6 3 V adjust knob until the voltmeter reads 3 5 V This sets Vy 3 5 V Filament Voltage Note The Argon Tube Enclosure may have a different suggested filament volt age If so use it instead of 3 5 V On Power Supply I rotate the 4 5 30 V adjust knob until the voltmeter reads 1 5 V This sets Voi 1 5 V the volt age between the first grid and the cathode Rotate the 0 12 V adjust knob until the voltmeter reads 10 0 V to set Vg24 10 0 V Retarding voltage Rotate the 0 100 V adjust knob until the voltmeter read
25. ted settings for the experiment but other values could be tried You can do the experiment by parameters that are marked on the Argon Tube Enclosure PASCONEE tt SE 9639 Franck Hertz Experiment Manual Measurements Note e During the experiment pay attention to the output current ammeter when the voltage is over 60 V If the ammeter s reading increases suddenly decrease the voltage at once to avoid the damage to the tube If you want to change the value of Ve64x Veza and Vy during the experiment rotate the 0 100 V adjust knob fully counter clockwise before making the changes The filament voltage is tunable from 0 to 6 3V If the anode output current is too high and causes the amplifier to overflow the filament voltage should be decreased As soon as you have finished the experiment return the VG2A voltage to 0 V to prolong the life of the argon tube 1 Increase the accelerating voltage Vg2x by a small amount for example 1 V Record the new accelerating voltage VG2k value read on voltmeter and current I read on Ammeter in Table 1 1 Continue to increase the voltage by the same small increment and record the new voltage and current each time in Table 1 1 Stop when the accelerating voltage VG2k 85V If the current I exceeds the range reduce the filament voltage for example 0 1 V and start over again 2 Try to identify the peak positions 1 e watch for those values of the accelerating volta
26. ting any cords or cables be sure that all power switches on the Power Supplies and Current Amplifier are in the OFF position and all voltage con trols are turned fully counterclockwise See the next page for numbered instructions about connecting cables and cords DC CURRENT AMPLIFIER Brolight SE 6621 SE 9650 Current Amplifier Argon Tube Enclosure BroLight Analog Port A FRANCK HERTZ TUBE BroLight 12 V DC Output V SE 9644 Power supply Il 100 V DC Output FILAMEN Analog Port B UNABLE DC Constant Voitage POWER SUPPLY BroLight Ve V SE 6615 a Power Supply DO 6 SPA 4 5 30 V DC Output A _ _ A _ ___JJJ 0 6 3 VDC Output PASG Oi 012 14264A l SE 9639 Franck Hertz Experiment On the DC Current Amplifier connect the special BNC to BNC cable between the port on the amplifier marked INPUT SIGNAL and the port on the Argon Tube Enclosure marked uA On Power Supply II SE 9644 connect the positive terminal of the 12 V DC output to the grid like electrode labeled G2 red sockets on the Argon Tube Enclosure SE 9650 and connect the negative terminal of the 12 V DC output to the terminal labeled A black sockets on the enclosure On Power Supply II connect the positive terminal of the 100 V DC output on the power supply to the grid like electrode labeled G2 red socket
27. z Experiment e Output Output power e Data Interface Connect to the analog channels of the PASCO 850 Universal Interface DC Current Amplifier Signal Switch Ammeter DC CURRENT AMPLIFIER Brolight Power i Switch A PASCO 850 Universal FS Interface CURREN RANGES CURREN ADJUST INPUT SIGNAL Port Me Sy AT ips INTERFACE Switch o Adjust e Power Switch Turns the power to the instrument ON or OFF e Data Interface Connect to the analog channels of the PASCO 850 Universal Interface Current Range Switch Sets the current range for the instrument s current amplifier 108 to 10719 A e Signal Switch Sets the signal to MEASURE Ll or CALIBRATION e Current Adjust Sets the current through the instrument to zero e Ammeter Displays the current through the argon tube e Input Signal Input current signal Franck Hertz Experiment Experiment Procedure 1 Experiment Procedure 1 Adjust Operating Voltages Note Before switching on the power be sure that all voltage controls are turned fully counterclockwise 1 Connect all the cables and cords as shown in the section Connect Cables and Cords page 7 2 On the Tunable DC Constant Voltage Power Supply I Tunable DC Constant Volt age Power Supply II and the DC Current Amplifier push in the Power Switch to the ON position 3 On the DC Current Amplifier turn the CURRENT RANGES switch to 10 19 A To set l l the current amplifier to
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