Instruction Manual 012-14264A Franck-Hertz Experiment Model SE-9639 Brolight Technology Co.
Table of Contents Equipment List - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Limited Warranty and Limitation of Liability - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2 Safety Information - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2 Installation and Maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3 Introduction - - - - - - - -
Instruction Manual 012-14264A Franck-Hertz Experiment SE-9639 Select: CURRENT RANGES 4 Select: MEASURE Adjust: CURRENT CALIBRATION Select: -4.5 V – 0 V 3 -4.5 V – +30 V 2 1 Adjust: 0 – 6.3 V Adjust: -4.5 V – 0 V and -4.5 V – +30 V Adjust: 0 – 12 V Adjust: 0 – 100 V and 0 – 200 V Select: 0 – 100 V 0 – 200 V 5, 6, 7, 8 9 Equipment List Included Equipment Model Quantity 1. Tunable DC (Constant Voltage) Power Supply I SE-6615 1 2.
SE-9639 Franck-Hertz Experiment Recommended Items Item Model Quantity 850 Universal Interface UI-5000 1 PASCO Capstone Software UI-5400 1 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.
Franck-Hertz Experiment Electrical Symbols • Special note: If a dangerous voltage is applied to an input terminal, then the same voltage may occur at all other terminals. Electrical Symbols Alternating Current Direct Current Caution, risk of danger, refer to the operating manual before use. Caution, possibility of electric shock Earth (ground) Terminal Protective Conductor Terminal Chassis Ground Conforms to European Union directives.
SE-9639 Franck-Hertz Experiment Replace the Argon Tube • Use a flat-blade screwdriver to remove the two small screws that hold the back plate onto the argon tube enclosure. • Use a small flat-blade screwdriver to pry the back panel off of the enclosure. • Pull up on the elastic pressing spring and rotate it off the argon tube. • Gently pull out the argon tube. • Then, install a new tube and replace the elastic pressing spring. • Finally, close the case and replace the two small screws.
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 for electrons passing through mercury vapor”, and a corresponding emission at the ultraviolet line (= 254 nm) of mercury. As it is not possible to observe the light emission directly, demonstrating this phenomenon requires extensive and cumbersome experiment apparatus.
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.
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 connecting 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 controls are turned fully counterclockwise. See the next page for numbered instructions about connecting cables and cords.
SE-9639 Franck-Hertz Experiment 1. 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 “A”. 2. 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.
Franck-Hertz Experiment Tunable DC (C onstant Voltage) Power Sup p ly I Tunable DC (Constant Voltage) Power Supply I Voltmeter Voltage Range Switch Voltmeter Power Switch PASCO 850 Universal Interface Ports Voltage Adjust Output 0 – 6.3 V Voltage Adjust Output -4.5 – 0 V -4.5 – +30 V • Voltmeter: Displays voltage across the argon tube. • Voltage Range Switch: Sets the voltage range as -4.5 – 0 V ( • Power Switch: Turns the power to the instrument ON or OFF.
SE-9639 Franck-Hertz Experiment • Output: Output power. • Data Interface: Connect to the analog channels of the PASCO 850 Universal Interface. DC Current Amplifier Signal Switch Ammeter Power Switch PASCO 850 Universal Interface Port Current Ranges Switch Current Adjust Input Signal • Power Switch: Turns the power to the instrument ON or OFF. • Data Interface: Connect to the analog channels of the PASCO 850 Universal Interface.
Franck-Hertz Experiment Ex periment Procedu r e 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 Voltage) Power Supply II, and the DC Current Amplifier, push in the Power Switch to the ON position. 3.
SE-9639 Franck-Hertz Experiment Manual Measurements Note: • 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 VG1K, VG2A and VH 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.
Franck-Hertz Experiment Questions 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 (V0). V2 – V1 + V3 – V2 + V4 – V3 + V5 – V4 + V6 – V5 V 0 = ---------------------------------------------------------------------------------------------------------------------------------------------------5 4.
SE-9639 Franck-Hertz Experiment Experiment Procedure 2 Using a PASCO Interface and Data Acquisition Software Current Amplifier Interface Port Argon Tube Enclosure Power Supply I Analog Input A 850 Universal Interface Analog Input B Power Supply II 8-pin DIN Extension Cable Items Needed Item* Quantity 850 Universal Interface (UI-5000) 1 PASCO Capstone Software (UI-5400) 1 *See the PASCO web site at www.pasco.
Franck-Hertz Experiment Software Setup 3. 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. 4. Turn ON the power for the Universal Interface, the power supplies, and the current amplifier. 5. On the DC Current Amplifier, turn the CURRENT RANGES switch to 10-10 A. To set the current amplifier to zero, press the SIGNAL button in to CALIBRATION.
SE-9639 • Franck-Hertz Experiment 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 VG2K is 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.
Franck-Hertz Experiment Analysis 012-14264A 17
SE-9639 Franck-Hertz Experiment Appendix A: General Specifications Item Description Supply voltage: 110 – 120 V or 220 – 240 V Supply voltage fluctuations: ±10% Fuse protection for inputs: 250 V T2A Display: 3-1/2 or 4-1/2 digit display Using site: Indoor use Temperature: Operating: 0°C to 40°C, Storage: -20°C to 50°C Relative humidity: Noncondensing < 10°C, 90% from 10°C to 30°C, 75% from 30°C to 40°C Pollution degree: 2 Certifications CE Safety compliance: IEC/EN 61010-1 Overvoltag
Franck-Hertz Experiment Appe ndix B: Teacher’s Notes Appendix B: Teacher’s Notes Sample Data 1: Manual Measurements Filament voltage (V) = 3.55 V VG1K = 1.5 V VG2A = 11.
SE-9639 Franck-Hertz Experiment Table 2: Peak and Valley Voltages Peak positions Valley positions V1 V2 V3 V4 V5 V6 VG2K (V) 22.5 32 43 55 66 79 IA (x 10-10 A) 153 448 825 1216 1522 1760 VG2K (V) 13 26 38 49 61 73 IA (x 10-10 A) 1 118 145 113 118 227 Analysis Obtain the value of argon atom’s first excitation potential (V0): V0(peak) = (V6- V1)/5 = 11.3 V; V0(valley) = (V6- V1)/5 = 12.0 V; Therefore: V0 = 11.
Franck-Hertz Experiment Sample Da ta 2 : U sin g a P ASC O 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•U0. 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.
SE-9639 Franck-Hertz Experiment Analysis Obtain the value of argon atom’s first excitation potential: V0 = 11.44 V; Calculate the value of Planck’s Constant, h V0 h = e ------ c where e = 1.602 x 10-19 C, = 108.1 nm, and c = 3 x 108 m/s. Based on the data, Planck’s Constant, h = 6.604 x 10-34 J•s Calculate the percent difference between the experimental value and the accepted value (h0 =6.626 x 10-34 J•s) h = | (h - h0) / h0 | x 100% = 0.3%. Using V0 = 11.44 + 0.50 V = 11.94 V gives h = 6.
Franck-Hertz Experiment Appe ndix 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.
