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Pasco Scientific TD-8553 Скачать руководство пользователя страница 19

15

012-04695D

Thermal Radiation System

Data and Calculations

①

Calculate R, the resistance of the filament at each of the voltage settings used (R = V/I).
Enter your results in Table 3.1.

②

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.

③

*Calculate T

4

for each value of T and enter your results in the table.

④

*On a separate sheet of paper, construct a graph of Rad versus T

4

. Use Rad as your dependent

variable (y-axis).

*In place of calculations

①

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

①

What is the relationship between Rad and T? Does this relationship hold over the entire
range of measurements?

②

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?

③

What sources of thermal radiation, other than the lamp filament, might have influenced your
measurements? What affect would you expect these sources to have on your results?

a

= 4.5 x 10

-3

K

-1

T

ref

(room temperature) = _______ K

(K = °C + 273)

R

ref

(filament resistance at T

ref

) = ________

Ω

V

I

Rad

R

T

T

4

(Volts)

(Amps)

(mV)

(Ohms)

(K)

(K

4

)

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

Table 3.1

Data

Calculations

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...
17
18
19
20
21
...
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Содержание TD-8553

Страница 1: ...STEM TD 8554A Radiation Cube Leslie s Cube TD 8553 Radiation Sensor TD 8555 STEFAN BOLTZMAN LAMP CAUTION 13 VDC MAX LAMP VOLTAGE FOR MAXIMUM ACCURACY MEASURE VOLTAGE AT BINDING POSTS USE NO 1196 BULB TD 8555 Stefan Boltzman Lamp Instruction Manual and Experiment Guide for the PASCO scientific Model TD 8553 8554A 8555 Includes Teacher s Notes and Typical Experiment Results ...

Страница 2: ... that may be of sufficient magnitude to constitute a risk of electric shock to persons 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...

Страница 3: ...tion Sensor 1 Thermal Radiation Cube Leslie s Cube 2 Stefan Boltzmann Lamp 3 Experiments Experiment 1 Introduction to Thermal Radiation 5 Experiment 2 Inverse Square Law 9 Experiment 3 Stefan Boltzmann Law high temperature 13 Experiment 4 Stefan Boltzmann Law low temperature 17 Teacher s Guide 19 Technical Support Inside Back Cover ...

Страница 4: ... 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 Copyright Warranty andEquipmentReturn Please Feel free to duplicate this manual subject to the copyright restrictions below Equipment Return Should the product have to be returned to PASCO scientific for any reason notify PASCO scientif...

Страница 5: ... C Maximum Incident Power 0 1 Watts cm2 Spectral Response 6 to 30µm Signal Output Linear from 10 6 to 10 1 Watts cm2 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 th...

Страница 6: ... 513 6 115 3 411 0 116 3 311 8 117 3 215 8 118 3 123 0 119 3 033 3 120 2 946 5 121 2 862 5 122 2 781 3 123 2 702 7 124 2 626 6 125 2 553 0 126 2 481 7 127 2 412 6 128 2 345 8 129 Therm Temp Res Ω C Therm Temp Res Ω C Therm Temp Res Ω C Therm Temp Res Ω C Therm Temp Res Ω C Therm Temp Res Ω C 207 850 10 197 560 11 187 840 12 178 650 13 169 950 14 161 730 15 153 950 16 146 580 17 139 610 18 133 000 ...

Страница 7: ...mbient 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 temper...

Страница 8: ...6 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 3...

Страница 9: ...eter 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 kΩ 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...

Страница 10: ... 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 Therm Res Therm Res Temperature Therm Res Temperature Temperature Therm Res Temperature Ω C Ω C Sensor Reading...

Страница 11: ...stions Part 2 Do different objects at approximately the same temperature emit different amounts of radiation 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 resul...

Страница 12: ...8 Thermal Radiation System 012 04695D Notes ...

Страница 13: ...n Sensor so it is at the same level as the filament of the Stefan BoltzmannLamp 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...

Страница 14: ...d the lamp to each of the settings listed in Table 2 2 At each setting record the reading on the millivoltmeter ä 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 Table 2 2 Radiation Level versus Distance X Ambient Radiation Leve...

Страница 15: ... axis If your graph from part 3 is not linear make a graph of Radiation Level versus 1 X2 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 ...

Страница 16: ...12 Thermal Radiation System 012 04695D Notes ...

Страница 17: ...5 6703 x 10 8 W m 2 K 4 In this experiment you will make relative measurements of the power per unit area emitted from 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...

Страница 18: ...ts 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 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 I the a...

Страница 19: ...us 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 ...

Страница 20: ...16 Thermal Radiation System 012 04695D Notes ...

Страница 21: ...duced by the sensor is proportional to the radia tion striking the detector minus the radiation leaving it Mathemati cally the sensor voltage is propor tional to Rnet Rrad Rdet s T4 Tdet 4 As long as you are careful to shield the Radiation Sensor from the Radiation Cube when measure ments are not being taken Tdet will be very close to room temperature Trm Procedure Set up the equipment as shown in...

Страница 22: ...mal Radiation Cube determine Tc the temperature in degrees Centigrade corresponding to each of your thermistor resistance measurements For each value of Tc determine Tk 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 Trm CalculateTk 4 for each value of Tk and record the values in the table Calculate T...

Страница 23: ...andard Error Black 100 White 96 86 1 21 Dull 20 23 2 17 Polished 7 38 1 82 Measurements are consistent with the rule The bet ter reflectors poorer absorbers are poor emitters Notes on Questions Part 2 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 aluminu...

Страница 24: ...s completely within the beam Notes on Questions 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 infrar...

Страница 25: ...or 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...

Страница 26: ...Thermal Radiation System 012 04695D 22 Notes ...

Страница 27: ...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 If your problem relates to the instruction manual note Part number and Revision listed by month and year on the front cover Have the manual at hand to discuss your questions Feed Back If you have any comments about this p...

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