PASCO Specialty & Mfg. TD-8555 User's Manual
Contents
1. Includes Teachers Notes Instruction Manual and M ExperinenResuts Experiment Guide for the PASCO scientific Model TD 8553 8554A 8555 THERMAL RADIATION SYSTEM TD 8554A Radiation Cube Leslie s Cube TD 8555 STEFAN BOLTZMAN LAMP CAUTIO 1 MAX LAMP Vi CAUTION HOT ON NV TD 8555 Stefan Low HIGH Boltzman Lamp TD 8553 Radiation Sensor 1988 PASCO scientific better D better 4 e 10101 Foothills Blvd Roseville CA 95747 7100 scientific Phone 916 786 3800 FAX 916 786 8905 www pasco com The lightning flash with arrowhead within an equilateral triangle is intended to alert the user of the presence of uninsulated dangerous voltage within the product s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN CAUTION TO PREVENT THE RISK OF ELECTRIC SHOCK DO NOT REMOVE BACK COVER NO USER SERVICEABLE PARTS INSIDE REFER SERVICING TO QUALIFIED SERVICE PERSONNEL The exclamation point within an equi lateral triangle is intended to alert the user of the presence of important operating and maintenance servic ing instructions in the literature ac companying the appliance 012 04695D Thermal Radiation System Table of Contents oer T Page Copyright and Warranty Equipment Return eene tis c2. 2 A min 3 A max TD 8555 STEFAN BOLTZMAN LAMP CAUTION 13 VDC MAX LAMP VOLTAGE FOR MA CY MEASURE YOLTRCE AT BINDING POSTS USE NO 1196 BULB Ek Figure3 Stefan Boltzmann Lamp REPLACEMENT BULB GE Lamp No 1196 available at most auto parts stores NOTE When replacing the bulb the leads should be soldered to minimize resistance For large temperature differences therefore deter mine the temperature of the tungsten filament as follows Accurately measure the resistance Rop of the tung sten filament at room temperature about 300 K Accuracy is important here A small error in Rp will result in a large error in your result for the fila ment temperature When the filament is hot measure the voltage and current into the filament and divide the voltage by the current to measure the resistance R G Divide R by R to obtain the relative resistance RYR Using your measured value for the relative resistiv ity of the filament at temperature T use Table 2 on the following page or the associated graph to de termine the temperature of the filament Thermal Radiation System 012 04695D Table 2 Temperature and Resistivity for Tungsten R P aook Temp K Resistivity uQ cm R R ook Temp Resistivity K uQ cm R R 300K Temp K Resistivity uQ cm P R 300K Temp Resistivity uQ cm 1 0 1 43 1 87 2 34 2 85 3 36
3. scientific 21 Calculations Radiation mV f x 1 235365E 9 x 1 396775E 1 R 2 9 881626E 1 2000000000 4000000000 6000000000 8000000000 10000000000 12000000000 14000000000 Difference in T 4 Notes on Questions The linearity of this graph indicates that the Stefan Boltzmann equation is correct even at low tempera tures The graph should be straight with some statistical variations Thermal Radiation System 012 04695D 22 1867 1e9 scientific Feed Back If you have any comments about this product or this 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 cus tomer feed back 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 Technical Support Contacting Technical Support Before you call the PASCO Technical Support staff it would be helpful to prepare the following information f your problem is computer software related note Title and Revision Date of software Type of Computer Make Model Speed Type of external Cables Peripherals f 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
4. 3 88 4 41 4 95 1 1 300 400 500 600 700 800 900 000 100 5 65 8 06 10 56 13 23 16 09 19 00 21 94 24 93 27 94 5 48 6 03 6 58 7 14 7 71 8 28 8 86 9 44 10 03 1200 1300 1400 1500 1600 1700 1800 1900 2000 30 98 34 08 37 19 40 36 43 55 46 78 50 05 53 35 56 67 10 63 11 24 11 84 12 46 13 08 13 72 14 34 14 99 15 63 2100 2200 2300 2400 2500 2600 2700 2800 2900 60 06 63 48 66 91 70 39 73 91 77 49 81 04 84 70 88 33 16 29 16 95 17 62 18 28 18 97 19 66 26 35 3000 3100 3200 3300 3400 3500 3600 92 04 95 76 99 54 103 3 107 2 111 1 115 0 Relative Resistivity Rt R 300K 20 Temperature versus Resistivity for Tungsten 19 18 17 16 15 14 13 12 11 10 500 1000 1500 2000 Temperature Kelvin 2500 3000 3500 PASCC scientific 012 04695D Thermal Radiation System Experiment 1 Introduction to Thermal Radiation EQUIPMENT NEEDED Radiation Sensor Thermal Radiation Cube Millivoltmeter Window glass Ohmmeter NOTES If lab time is short it s helpful to preheat the cube at a setting of 5 0 for 20 minutes before the
5. I the ammeter reading and Rad the reading on the millivoltmeter IMPORTANT Make each Sensor reading quickly Between readings place both sheets of insulating foam between the lamp and the Sensor with the silvered surface facing the lamp so that the temperature of the Sensor stays relatively constant 14 PASCC scientific 012 04695D Thermal Radiation System Data and Calculations D Calculate R the resistance of the filament at each of the voltage settings used R V D Enter your results in Table 3 1 Use the procedure on pages 3 and 4 of this manual to determine T the temperature of the lamp filament at each voltage setting Enter your results in the table G Calculate T for each value of T and enter your results in the table On a separate sheet of paper construct a graph of Rad versus T Use Rad as your dependent variable y axis In place of calculations and some may prefer to perform a power regression on Rad versus T to determine their relationship or graph on log log paper and find the slope Questions What is the relationship between Rad and T Does this relationship hold over the entire range of measurements The Stefan Boltzmann Law is perfectly true only for ideal black body radiation A black body is any object that absorbs all the radiation that strikes it Is the filament of the lamp a true black body amp What sources of thermal radiation other than t
6. 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 This makes descriptions of individual parts much easier f 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 questions
7. in order to determine the contribution from the lamp alone Turn on the power supply to illuminate the lamp Set the voltage to approximately 10 V IPASGG i scientific Thermal Radiation System 012 04695D IMPORTANT Do not let the voltage to the lamp exceed 13 V Adjust the distance between the Sensor and the lamp to each of the settings listed in Table 2 2 At each setting record the reading on the millivoltmeter IMPORTANT Make each reading quickly Between readings move the Sensor away from the lamp or place the reflective heat shield between the lamp and the Sensor so that the temperature of the Sensor stays relatively constant X Ambient Radiation Level X Rad 1 X2 Rad Ambient cm mV cm mV cm mV 10 2 5 20 3 0 30 40 3 5 50 4 0 60 4 5 70 50 80 90 6 0 100 7 0 Average Ambient 8 0 Radiation Level 9 0 Table 2 1 10 0 Ambient Radiation Level 12 0 14 0 16 0 18 0 20 0 25 0 30 0 35 0 40 0 45 0 50 0 60 0 70 0 80 0 90 0 Table 2 2 Radiation Level versus Distance 100 0 10 PASCC scientific 012 04695D Thermal Radiation System Calculations For each value of X calculate 1 X Enter your results in Table 2 2 Subtract the Average Ambient Radiation Level from each of your Rad measurements in Table 2 2 Enter your results in the table amp Ona separate sheet of paper make a graph of R
8. 7 48 905 4l 18 668 65 7 969 1 89 3 729 7 113 1 880 9 137 139 610 18 46 863 42 17 980 66 7 707 7 90 3 619 8 114 1 830 5 138 133 000 19 44 917 43 17 321 67 7 456 2 91 3 513 6 115 1 781 7 139 126 740 20 43 062 44 16 689 68 72140 92 3 411 0 116 1 734 3 140 120 810 21 41 292 45 16 083 69 6 980 6 93 3 311 8 117 1 688 4 141 115 190 22 39 605 46 15 502 70 6 755 9 94 3 215 8 118 1 643 9 142 109 850 23 37 995 47 14 945 71 6 5394 95 3 123 0 119 1 600 6 143 104 800 24 36 458 48 14 410 72 6 330 8 96 3 033 3 120 1 558 7 144 100 000 25 34 991 49 13 897 73 6 129 8 97 2 946 5 121 1 5180 145 95 447 26 33 591 50 13 405 74 5 936 1 98 2 862 5 122 1 478 6 146 91 126 27 32 253 51 12 932 75 5 749 3 99 2 781 3 123 1 440 2 147 87 022 28 30 976 52 12 479 76 5 569 3 100 2 702 7 124 1 403 0 148 83 124 29 29 756 53 12 043 77 5 395 6 101 2 626 6 125 1 366 9 149 79 422 30 28 590 54 11 625 78 5 228 1 102 2 553 0 126 1 331 9 150 75 903 31 27 475 55 11 223 79 5 066 6 103 2481 7 127 72 560 32 26 409 56 10 837 80 4910 7 104 2 412 6 128 69 380 33 25 390 57 10 467 81 4 760 3 105 2 345 8 129 2 PASC C scientific 012 04695D Thermal Radiation System Stefan Boltzmann Lamp IMPORTANT The voltage into the lamp should NEVER exceed 13 V Higher voltages will burn out the filament The TD 8555 Stefan Boltzmann Lamp Figure 3 is a high temperature source of thermal radiation The lamp can be used for high temperature investigations of the Ste
9. SCO scientific 012 04695D Thermal Radiation System Experiment 2 Inverse Square Law EQUIPMENT NEEDED Radiation Sensor Stefan Boltzmann Lamp Millivoltmeter Power Supply 12 VDC 3 A meter stick Align axes of filament and Sensor E HD E Top View Power Supply 13 V MAX Millivoltmeter Meter Stick Align zero point of meter stick with center of filament Figure 2 1 Equipment Setup D Setup the equipment as shown in Figure 2 1 a Tape a meter stick to the table b Place the Stefan Boltzmann Lamp at one end of the meter stick as shown The zero point of the meter stick should align with the center of the lamp filament c Adjust the height of the Radiation Sensor so it is at the same level as the filament of the Stefan Boltzmann Lamp d Align the lamp and sensor so that as you slide the Sensor along the meter stick the axis of the lamp aligns as closely as possible with the axis of the Sensor e Connect the Sensor to the millivoltmeter and the lamp to the power supply as indicated in the figure With the lamp OFF slide the sensor along the meter stick Record the reading of the millivolt meter at 10 cm intervals Record your values in Table 2 1 on the following page Average these values to determine the ambient level of thermal radiation You will need to subtract this average ambient value from your measurements with the lamp on
10. Setting 10 0 Therm Res Therm Res Q Therm Res Q Therm Res Q Temperature Temperature C Temperature C Temperature C Sensor Sensor Sensor Sensor Surface Reading Surface Reading Surface Reading Surface Reading mV mV mV mV Black Black Black Black White White White White Polished Polished Polished Polished Aluminum Aluminum Aluminum Aluminum Dull Dull Dull Dull Aluminum Aluminum Aluminum Aluminum PASCO scientific 012 04695D Thermal Radiation System Questions Part 1 D List the surfaces of the Radiation Cube in order of the amount of radiation emitted Is the order independent of temperature Itis a general rule that good absorbers of radiation are also good emitters Are your measure ments consistent with this rule Explain Questions Part 2 D Do different objects at approximately the same temperature emit different amounts of radiation Q Can you find materials in your room that block thermal radiation Can you find materials that don t block thermal radiation For example do your clothes effectively block the thermal radiation emitted from your body Absorption and Transmission of Thermal Radiation Questions What do your results suggest about the phenomenon of heat loss through windows What do your results suggest about the Greenhouse Effect PASC C 7 scientific Thermal Radiation System 012 04695D PA
11. adiation Level versus Distance from Source using columns one and four from Table 2 2 Let the radiation level be the dependent y axis If your graph from part 3 is not linear make a graph of Radiation Level versus 1 X using columns three and four from table 2 2 Questions Which of the two graphs is more linear Is it linear over the entire range of measurements The inverse square law states that the radiant energy per unit area emitted by a point source of radiation decreases as the square of the distance from the source to the point of detection Does your data support this assertion amp Is the Stefan Boltzmann Lamp truly a point source of radiation If not how might this affect your results Do you see such an effect in the data you have taken LEIHO 11 scientific Thermal Radiation System 012 04695D 12 18 7 189 scientific 012 04695D Thermal Radiation System Experiment 3 Stefan Boltzmann Law high temperature EQUIPMENT NEEDED Radiation Sensor Stefan Boltzmann Lamp Ohmmeter Ammeter 0 3 A Voltmeter 0 12 V Millivoltmeter Ohmmeter Thermometer Introduction The Stefan Boltzmann Law relates R the power per unit area radiated by an object to T the absolute temperature of the object The equation is R oT s 5 6703 xi 2 4 mK In this experiment you will make relative measurements of the power per unit area emitted fro
12. btion and Transmission of Thermal Radiation Heat loss through closed windows is primarily conductive Although the glass tested transmitted some infrared most was blocked Q A greenhouse allows light in but does not allow much heat to escape This phenomenon is used to grow tropical plants in cold climates Experiment 2 Inverse Square Law Calculations 30 f x 2 060229E 2 x 1 815646E40 254 4 R 2 9 822989E 1 S 204 E 4j 15 T p 4 o 1 1 ei 1 li 5 T 3 1 0 E 11 i 0 10 20 30 40 50 Distance cm LEIHO scientific 19 Radiation mV E N N eo oa eo oa a 0 06 0 08 1 x 2 0 1 0 12 0 14 0 16 Thermal Radiation System 012 04695D Notes on Questions The graph of Radiation versus 1 x is more linear but not over the entire range There is a distinct falloff in intensity at the nearer distances due to the non point characteristics of the lamp A graph of Radiation versus 1 x using only data points from 10cm or more is nearly linear If we use data from distances that are large com pared to the size of the lamp filament so that the filament is effectively a point then this data sup ports the hypothesis The Stefan Boltzmann Lamp is not truly a point source If it were not then there would be a falloff in light level for measurements taken close to the lamp This falloff can be seen in our data Suggestion The largest pa
13. critical such as Experiment 3 two small sheets of opaque insulating foam have been provided Place this heat shield in front of the sensor when measurements are not actively being taken IZEN scientific The two posts extending from the front end of the Sensor protect the thermopile and also provide a reference for positioning the sensor a repeatable distance from a radiation source Specifications Temperature Range 65 to 85 C Maximum Incident Power 0 1 Watts cm Spectral Response 6 to 30um Signal Output Linear from 10 to 10 Watts cm Thumbscrew Loosen to reposition Sensor or to remove Sensor from stand Shutter Ring Slide forward to open shutter Shutter Banana Connectors Connect to millivolt meter Figure 1 Radiation Sensor Thermal Radiation System 012 04695D The TD 8554A Radiation Cube Figure 2 provides four different radiating surfaces that can be heated from room temperature to approximately 120 C The cube is heated by a 100 watt light bulb Just plug in the power cord flip the toggle switch to ON then turn the knob clockwise to vary the power Measure the cube temperature by plugging your ohmmeter into the banana plug connectors labeled THERMISTOR The thermistor is embedded in one corner of the cube Measure the resistance then use Table 1 below to translate the resistance reading into a temperature measurement An abbreviate
14. d version of this table is printed on the base of the Radiation Cube NOTE For best results a digital ohmmeter should be used See the current PASCO catalog for recommended meters IMPORTANT When replacing the light bulb use a 100 Watt bulb Bulbs of higher power could damage the cube Thermal Radiation Cube Leslie s Cube CAUTION Cube may be HOT Flip toggle switch to ON to turn on power Turn knob clockwise to increase Low HIGH To 115 or 7_ 200 VAG Banana Connectors Measure thermistor resistance Use table on back to determine cube temperature Figure 2 Radiation Cube Leslie s Cube Table 1 Resistance versus Temperature for the Thermal Radiation Cube Therm Temp Therm Temp Therm Temp Therm Temp Therm Temp Therm Temp Res Q C Res Q C Res Q C Res Q C Res Q C Res Q C 207 850 10 66 356 34 24 415 58 10 110 82 4 615 1 106 2 281 0 130 197 560 11 63 480 35 23 483 59 9 767 2 83 4 475 0 107 2218 3 131 187 840 12 60 743 36 22 590 60 9 437 7 84 4 339 7 108 2 157 6 132 178 650 13 58 138 37 21 736 61 9 120 8 85 4 209 1 109 2 098 7 133 169 950 14 55 658 38 20 919 62 8 816 0 86 4 082 9 110 2 041 7 134 161 730 15 53 297 39 20 136 63 8 5227 87 3 961 1 111 1 986 4 135 153 950 16 51 048 40 19 386 64 8 240 6 88 3 8434 112 1 932 8 136 146 580 1
15. 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 post age or freight prepaid Damage caused by improper packing of the equipment for return shipment will not be covered by the warranty Shipping costs for return ing the equipment after repair will be paid by PASCO scientific Credits This manual authored by Bruce Lee Teacher s guide written by Eric Ayres 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 ship ping 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
16. fan Boltzmann Law The high temperature simplifies the analysis because the fourth power of the ambient temperature is negligibly small compared to the fourth power of the high temperature of the lamp filament see Experiments 3 and 4 When properly oriented the filament also provides a good approxima tion to a point source of thermal radiation It therefore works well for investigations into the inverse square law By adjusting the power into the lamp 13 Volts max 2 A min 3 A max filament temperatures up to approxi mately 3 000 C can be obtained The filament temperature is determined by carefully measuring the voltage and current into the lamp The voltage divided by the current gives the resistance of the filament Equipment Recommended AC DC LV Power Supply SF 9584 or equivalent capable of 13 V 3 A max R Ref T2 T OR ef For small temperature changes the temperature of the tungsten filament can be calculated using a the temperature coefficient of resistivity for the filament where T Temperature R Resistance at temperature T T Reference temperature usually room temp Rg Resistance at temperature A a Temperature coefficient of resistivity for the filament 4 5 x 10 K for tungsten For large temperature differences however a is not constant and the above equation is not accurate PASCC scientific Banana Connectors Connect to Power Supply 13 V MAX
17. following rules D The packing carton must be strong enough for the item shipped Make certain there are at least two inches of pack ing material between any point on the apparatus and the inside walls of the carton Make 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 916 786 3800 FAX 916 786 3292 email techsupp pasco com web WWW pasco com 012 04695D Thermal Radiation System Introduction The PASCO Thermal Radiation System includes three items the TD 8553 Radiation Sensor the TD 8554A Radiation Cube Leslie s Cube and the TD 8555 Stefan Boltzmann Lamp This manual contains operating instructions for each of these items plus instructions and worksheets for the following four experiments Introduction to Thermal Radiation Q Inverse Square Law amp Stefan Boltzmann Law at high temperatures Stefan Boltzmann Law at low temperatures The Stefan Boltzmann law states that the radiant energy per unit area is proportional to the fourth power of the temperature of the radiating surface In addition to the equipment in the radiation system several standard laboratory items such as power supplies and meters are needed for most experiments Check the experiment section of this manual for informati
18. g slowly Read and record R the ohmmeter reading and Rad the millivoltmeter reading The readings should be taken as nearly simultaneously as possible while briefly removing the heat shield Record these values in Table 4 1 LEIHO 17 scientific Thermal Radiation System 012 04695D IMPORTANT Make each reading quickly removing the heat shield only as long as it takes to make the measurement Take care that the position of the sensor with respect to the cube is the same for all measurements Replace the heat shield and turn the cube power to 10 When the temperature has risen an additional 12 15 C repeat the measurements of step 5 Repeat this procedure at about 12 15 intervals until the maximum temperature of the cube is reached Data and Calculations Room Temperature R Q qe s K Table 4 1 Data Calculations R Rad T T TS ns mV CC K E E D Using the table on the base of the Thermal Radiation Cube determine T the temperature in degrees Centigrade corresponding to each of your thermistor resistance measurements For each value of T determine T the corresponding value in degrees Kelvin K C 273 Enter both sets of values in Table 4 1 above In the same manner determine the room tem perature T CalculateT for each value of T and record the values in the table amp Calculate T T for each value of T and record your results
19. he lamp filament might have influenced your measurements What affect would you expect these sources to have on your results a 4 5 x 10 K T room temperature K K C 273 R filament resistance at T Q Table 3 1 Data Calculations V I Rad R T T Volts Amps mV Ohms K K5 1 00 2 00 3 00 4 00 5 00 6 00 7 00 8 00 9 00 10 00 11 00 12 00 LEIHO 15 scientific Thermal Radiation System 012 04695D 16 18 7 189 scientific 012 04695D Thermal Radiation System Experiment 4 Stefan Boltzmann Law low temperature EQUIPMENT NEEDED Radiation Sensor Thermal Radiation Cube Millivoltmeter Ohmmeter Introduction In experiment 3 you investigated the Stefan Boltzmann Law R sT for the high temperatures attained by an incandescent filament At those high temperatures approxi mately 1 000 to 3 000 K the ambient temperature is small enough that it can be neglected in the analysis In this experiment you will investigate the Stefan Boltzmann relationship at much lower temperatures using the Thermal Radiation Cube At these lower temperatures the ambient temperature can not be ignored If the detector in the Radiation Sensor were operating at absolute zero temperature it would produce a voltage directly proportional to the intensity of the radiation that strikes it How ever the detector is not at abso
20. in the table 4 On separate sheet of paper construct a graph of Rad versus E T Use Rad as the depen dent variable y axis Questions What does your graph indicate about the Stefan Boltzmann law at low temperatures Is your graph a straight line Discuss any deviations that exist 18 PASCC scientific 012 04695D Thermal Radiation System Teacher s Guide Experiment 1 Introduction to Thermal Radiation Notes on Questions Part 1 D In order of decreasing emissivity the surfaces are Black White Dull Aluminum and Polished Alumi num This order is independent of temperature and within the temperature range tested the ratio of emissions between sides is almost constant The normalized percentages are as follows Black is defined as 10096 EN Surface Error LE Measurements are consistent with the rule The bet ter reflectors poorer absorbers are poor emitters Normalized Emissions Notes on Questions Part 2 D Yes All sides of the Leslie s Cube are at the same temperature but the polished side emits less than 10 as much radiation as the black side Materials that block thermal radiation well include aluminum foil styrofoam etc Materials that do not block radiation as well include air clothing etc All materials will block radiation to some degree but there are strong differences in how much is blocked Notes on Questions Absor
21. laboratory period begins A very quick method is to preheat the cube at full power for 45 minutes then use a small fan to reduce the temperature quickly as you lower the power input Just be sure that equilibrium is attained with the fan off Part 1 and 2 of this experiment can be performed simultaneously Make the measure ments in Part 2 while waiting for the Radiation Cube to reach thermal equilibrium at each of the settings in Part 1 When using the Radiation Sensor always shield it from the hot object except for the few seconds it takes to actually make the measurement This prevents heating of the thermo pile which will change the reference temperature and alter the reading Radiation Rates from Different Surfaces Part 1 Connect the Ohmmeter and Millivoltmeter as shown in Figure 1 1 Turn on the Thermal Radiation Cube and set the power switch to HIGH Keep an eye on the ohmmeter reading When it gets down to about 40 KQ reset the power switch to 5 0 If the cube is preheated just set the switch to 5 0 When the cube reaches thermal equilibrium the ohmmeter reading will fluctuate around a relatively fixed value use the Radiation Sensor to measure the radiation emitted from each of the four surfaces of the cube Place the Sensor so that the posts on its end are in contact with the cube surface this ensures that the distance of the measurement is the same for all surfaces Record your measuremen
22. lute zero temperature so it is also radiating thermal energy According to the Stefan Boltzmann law it radiates at a rate R e T sT The voltage produced by the cie sensor is proportional to the radia tion striking the detector minus the radiation leaving it Mathemati cally the sensor voltage is propor tional to R R a Raa S T TaD As long as you are careful to shield the Radiation Sensor from the Radiation Cube when measure ments are not being taken T will be very close to room temperature T Ohmmeter Heat Shield reflective side toward cube Millivoltmeter Procedure Figure 4 1 Equipment Setup D Setup the equipment as shown in Figure 4 1 The Radiation Sensor should be pointed directly at the center of one of the better radiating surfaces of the cube the black or white surface The face of the Sensor should be parallel with the surface of the cube and about 3 to 4 cm away With the Thermal Radiation Cube off measure R w the resistance of the thermistor at room temperature Enter this data in the space on the following page amp Shield the sensor from the cube using the reflecting heat shield with the reflective side of the shield facing the cube Turn on the Radiation Cube and set the power switch to 10 When the thermistor resistance indicates that the temperature is about 12 C above room temperature turn the power down so the temperature is changin
23. m a hot object namely the Stefan Boltzmann Lamp at various temperatures From your data you will be able to test whether the radiated power is really proportional to the fourth power of the temperature Most of the thermal energy emitted by the lamp comes from the filament of the lamp The filament temperature can be determined using the procedure given on pages 3 and 4 of this manual Ammeter Power Supply 13 V MAX Millivoltmeter Voltmeter 6cm Figure 3 1 Equipment Setup PASCO 13 scientific Thermal Radiation System 012 04695D Procedure IMPORTANT The voltage into the lamp should NEVER exceed 13 V Higher voltages will burn out the filament 0 BEFORE TURNING ON THE LAMP measure T p the room temperature in degrees Kelvin K C 273 and R p the resistance of the filament of the Stefan Boltzmann Lamp at room temperature Enter your results in the spaces on the following page Set up the equipment as shown in Figure 3 1 The voltmeter should be connected directly to the binding posts of the Stefan Boltzmann Lamp The Sensor should be at the same height as the filament with the front face of the Sensor approximately 6 cm away from the filament The entrance angle of the thermopile should include no close objects other than the lamp amp Turn on the power supply Set the voltage V to each of the settings listed in Table 3 1 on the following page At each voltage setting record
24. on on required equipment If you don t have all the items of the radiation system read through the operating instructions for the equip ment you do have then check the experiment section to determine which of the experiments you can per form A radiation sensor is required for all the experiments The PASCO TD 8553 Radiation Sensor Figure 1 measures the relative intensities of incident thermal radiation The sensing element a miniature thermo pile produces a voltage proportional to the intensity of the radiation The spectral response of the thermopile is essentially flat in the infrared region from 0 5 to 40 um and the voltages produced range from the micro volt range up to around 100 millivolts A good millivolt meter is sufficient for all the experiments described in this manual See the current PASCO catalog for recommended meters The Sensor can be hand held or mounted on its stand for more accurate positioning A spring clip shutter is opened and closed by sliding the shutter ring forward or back During experiments the shutter should be closed when measurements are not actively being taken This helps reduce temperature shifts in the thermopile reference junction which can cause the sensor response to drift Radiation Sensor NOTE When opening and closing the shutter it is possible you may inadvertently change the sensor position Therefore for experiments in which the sensor position is
25. oto aic perenne ii Totrod ct oN enssins Dc aaae 1 Radiation Sensor an onis atrae eeii n dete Mu Moe a Ra MUR e ees 1 Thermal Radiation Cube Leslie S Cube 2 ccsasiwsnaienascondassdencessea PE e et desde 2 visuri Eso i018 Lamp PME RT 3 Experiments Experiment 1 Introduction to Thermal Radiation e 5 Experiment 2 Inverse Squate La osugiere Drtviccie stages buena oE 9 Experiment 3 Stefan Boltzmann Law high temperature 13 Experiment 4 Stefan Boltzmann Law low temperature 17 Teacher CST eisai ea e e tare den seated eee 19 Technical SUpport osisssa Inside Back Cover PASC Oi i scientific Thermal Radiation System 012 04695D Copyright Warranty and Equipment Return Please Feel free to duplicate this manual subject to the copyright restrictions below Copyright Notice The PASCO scientific Model TD 8553 8554A 8555 Thermal Radiation System manual is copyrighted and all rights reserved However permis sion 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
26. p f x 8 141230E 13 x 4 006331E 0 5 10 R 2 z 9 974766E 1 gt 5 7 c 0 7 c 2 S 1 oO c 0 1 100 1000 10000 Temperature K PASCO scientific 012 04695D Thermal Radiation System The lamp filament is not a true black body If it were it would be completely and totally black at room temperature It is a fairly good approximation though as long as the temperature is high enough that the emitted light is much greater than the inci dent light Any other thermal source in the room would influ ence the results including the warm body of the ex perimenter and the room itself These introduce some error but it is small as long as the tempera ture of the lamp is high compared to the tempera ture of these other sources Experiment 4 Stefan Boltzmann Law at low temperatures Notes on Procedure amp Make sure that the Thermal Radiation Cube has been off for enough time to be at equilibrium with the room before making this measurement If the cube has been turned on recently use another ther mometer to make the measurement Use ridiculous precautions with this experiment It is impossible to have too much insulation between the cube and the sensor between measurements For our experiments we use two foam sheets covered with aluminum tape and an air gap between the sheets We never removed this heat shield for more than 5 seconds while taking a measurement PASC CQ
27. rt of the error in this lab is due to the non point nature of the Stefan Boltzmann Lamp You can approximate a much better point source with a laser and a converging lens j Point Source Laser For best results use a short focal length lens and make sure that the sensor is always completely within the beam Notes on Procedure Part 1 amp Between readings place the insulating material be tween the lamp and the sensor For best results use both sheets with the aluminum sides facing away from each other Remove the sheets for only enough time to take each measurement Calculations f x 5 521363E 14 x 4 363707E 0 R 2 9 979700E 1 Radiation Sensor Voltage O 200 400 600 800 1000 1200 1400 1600 1800 2000 Temperature K Experiment 3 Stefan Boltzmann Law at high temperatures 20 Notes on Questions D A power regression of our data shows a power of 4 36 However an analysis of only those points with temperature greater than 1500 shows a power of 4 01 This inaccuracy in the low temperature points is due to absorbtion of the infrared by the glass lamp bulb See experiment 1 This absorbtion is more significant at the lower temperatures where the infrared makes up a larger percentage of the en tire output First fit uses all data points 100 second uses only those 1500K or higher f x 5 521363E 14 x 4 363707E 0 L Dv R 2 9 979700E 1 am
28. ts in the appropriate table on the following page Also measure and record the resistance of the ther mistor Use the table on the base of the cube to determine the corresponding temperature Increase the power switch setting first to 6 5 then to 8 0 then to HIGH At each Millivoltmeter Ohmmeter Figure 1 1 Equipment Setup setting wait for the cube to reach thermal equilibrium then repeat the measurements of step 1 and record your results in the appropriate table PASC C scientific Thermal Radiation System 012 04695D Part 2 Use the Radiation Sensor to examine the relative magnitudes of the radiation emitted from various objects around the room On a separate sheet of paper make a table summarizing your observations Make measurements that will help you to answer the questions listed below Absorption and Transmission of Thermal Radiation D Place the Sensor approximately 5 cm from the black surface of the Radiation Cube and record the reading Place a piece of window glass between the Sensor and the bulb Does window glass effectively block thermal radiation Remove the lid from the Radiation Cube or use the Stefan Boltzmann Lamp and repeat the measurements of step 1 but using the bare bulb instead of the black surface Repeat with other materials Radiation Rates from Different Surfaces Data and Calculations Power Setting 5 0 Power Setting 6 5 Power Setting 8 0 Power
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