Pasco Scientific TD-8553 User manual

1
2
3456
7
8
LOW HIGH
CAUTION: HOT!
CAUTION
HOT!
THERMISTOR
Model TD-8554A
(LESLIE'S CUBE)
100W
BULB
MAX.
ON
OFF
©1988 PASCO scientific $5.00
012-04695D
03/99
THERMAL
RADIATION SYSTEM
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

2
Thermal Radiation 012-04695D
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
The lightning flash with arrowhead,
withinanequilateraltriangle,isintended
to alert the user of the presence of
uninsulated“dangerousvoltage”within
the product’s enclosure that may be of
sufficientmagnitude toconstitute arisk
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.
Theexclamation pointwithinan 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
i
Table of Contents
Section...................................................................................................... Page
Copyright and Warranty, Equipment Return.................................................. ii
Introduction .....................................................................................................1
Radiation 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

Thermal Radiation System 012-04695D
ii
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 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.
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 scientific by
letter, phone, or fax BEFORE returning the product.
Upon notification, the return authorization and ship-
ping instructions will be promptly issued.
ä NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATIONFROMPASCO.
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
followingrules:
➀The packing carton must be strong enough for the
item shipped.
➁Make certain there are at least two inches of pack-
ing material between any point on the apparatus and
the inside walls of the carton.
➂Make certain that the packing material cannot shift
in the box or become compressed, allowing the
instrument come in contact with the packing carton.
Address: PASCOscientific
10101 Foothills Blvd.
Roseville, CA 95747-7100
Phone: [phone]
FAX: [phone]
email: [email protected]
web: www.pasco.com
Credits
This manual authored by: Bruce Lee
Teacher’s guide written by: Eric Ayres

1
012-04695D Thermal Radiation System
Radiation Sensor
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:
①Introduction to Thermal Radiation,
②Inverse Square Law,
③Stefan-Boltzmann Law* (at high temperatures),
④Stefan-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
information 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 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/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 the infrared region (from 0.5 to 40
µm), 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.
ä 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
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. Figure 1 Radiation Sensor
Banana Connectors:
Connect to millivolt meter
Thumbscrew: Loosen to
reposition Sensor or to
remove Sensor from stand
Shutter
Shutter Ring: Slide
forward to open
shutter

2
Thermal Radiation System 012-04695D
Thermal Radiation Cube (Leslie’s Cube)
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 abbreviated version of
this table is printed on the base of the Radiation Cube.
ä NOTE: For best results, a digital ohmmeter
should be used. (See the current PASCO catalog
for recommended meters.)
ä IMPORTANT: When replacing the light
bulb, use a 100-Watt bulb. Bulbs of higher
power could damage the cube.
CAUTION: Cube may be HOT!
Figure 2 Radiation Cube (Leslie's Cube)
1
234567
8
LOW HIGH
CAUTION: HOT!
CAUTION
HOT!
THERMISTOR
Model TD-8554A
(LESLIE'S CUBE)
100W
BULB
MAX.
ON
OFF
Turn knob
clockwise to
increase
temperature.
Flip toggle
switch to
“ON” to turn
on power. Banana
Connectors:
Measure
thermistor
resistance.
Use table on
back to
determine
cube
temperature.
To 115
or
200
VAC
4,615.1 106
4,475.0 107
4,339.7 108
4,209.1 109
4,082.9 110
3,961.1 111
3,843.4 112
3,729.7 113
3,619.8 114
3,513.6 115
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 19
126,740 20
120,810 21
115,190 22
109,850 23
104,800 24
100,000 25
95,447 26
91,126 27
87,022 28
83,124 29
79,422 30
75,903 31
72,560 32
69,380 33
66,356 34
63,480 35
60,743 36
58,138 37
55,658 38
53,297 39
51,048 40
48,905 41
46,863 42
44,917 43
43,062 44
41,292 45
39,605 46
37,995 47
36,458 48
34,991 49
33,591 50
32,253 51
30,976 52
29,756 53
28,590 54
27,475 55
26,409 56
25,390 57
24,415 58
23,483 59
22,590 60
21,736 61
20,919 62
20,136 63
19,386 64
18,668 65
17,980 66
17,321 67
16,689 68
16,083 69
15,502 70
14,945 71
14,410 72
13,897 73
13,405 74
12,932 75
12,479 76
12,043 77
11,625 78
11,223 79
10,837 80
10,467 81
10,110 82
9,767.2 83
9,437.7 84
9,120.8 85
8,816.0 86
8,522.7 87
8,240.6 88
7,969.1 89
7,707.7 90
7,456.2 91
7,214.0 92
6,980.6 93
6,755.9 94
6,539.4 95
6,330.8 96
6,129.8 97
5,936.1 98
5,749.3 99
5,569.3 100
5,395.6 101
5,228.1 102
5,066.6 103
4,910.7 104
4,760.3 105
2,281.0 130
2,218.3 131
2,157.6 132
2,098.7 133
2,041.7 134
1,986.4 135
1,932.8 136
1,880.9 137
1,830.5 138
1,781.7 139
1,734.3 140
1,688.4 141
1,643.9 142
1,600.6 143
1,558.7 144
1,518.0 145
1,478.6 146
1,440.2 147
1,403.0 148
1,366.9 149
1,331.9 150
Table 1
Resistance versus Temperature for the Thermal Radiation Cube

3
012-04695D Thermal Radiation System
TD-8555
STEFAN-BOLTZMAN
LAMP
CAUTION
13 VDC MAX LAMP VOLTAGE
FOR MAXIMUM ACCURACY,
MEASURE VOLTAGE AT
BINDING POSTS
USE NO.1196 BULB
Stefan-Boltzmann Lamp
For large temperature differences, therefore, deter-
mine the temperature of the tungsten filament as
follows:
①Accurately measure the resistance (Rref) of the tung-
sten filament at room temperature (about 300 °K).
Accuracy is important here. A small error in Rref
will result in a large error in your result for the fila-
menttemperature.
②When the filament is hot, measure the voltage and
current into the filament and divide the voltage by
the current to measure the resistance (RT).
③Divide RTby Rref to obtain the relative resistance
(RT/Rref).
④Using 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.
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 Stefan-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
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
Tref = Reference temperature (usually room temp.)
Rref = Resistance at temperature Tref
a= Temperature coefficient of resistivity for the
filament (α= 4.5 x 10-3 K-1 for tungsten)
For large temperature differences, however, ais not
constant and the above equation is not accurate.
T = + Tref
R- Rref
aRref
REPLACEMENT BULB: GE Lamp No. 1196,
available at most auto parts stores.
ä NOTE: When replacing the bulb, the leads
should be soldered to minimize resistance.
PASCO scientific
Banana Connectors:
Connect to Power
Supply – 13 V MAX,
(2 A min, 3 A max)
Figure 3 Stefan-Boltzmann Lamp

4
Thermal Radiation System 012-04695D
0 500 1000 1500 2000 2500 3000 3500
Table 2 Temperature and Resistivity for Tungsten
Temperature versus Resistivity for Tungsten
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
R
T
R
300K
20
Temperature (Kelvin)
Relative
Resistivity
1.0
1.43
1.87
2.34
2.85
3.36
3.88
4.41
4.95
300
400
500
600
700
800
900
1000
1100
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
103.3
107.2
111.1
115.0
92.04
95.76
99.54
Temp
°K
R/R
300K
Resistivity
µΩ cm Temp
°K
R/R
300K
Resistivity
µΩ cm
Temp
°K
R/R
300K
Resistivity
µΩ cm
Temp
°K
R/R
300K
Resistivity
µΩ cm

5
012-04695D Thermal Radiation System
Experiment 1: Introduction to Thermal Radiation
EQUIPMENT NEEDED:
— Radiation Sensor, Thermal Radiation Cube — Window glass
— Millivoltmeter — Ohmmeter.
ä NOTES:
①If lab time is short, it's helpful to preheat the cube at a setting of 5.0 for 20 minutes before
the 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.)
②Part 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.
③When 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
①Connect the Ohmmeter and Millivoltmeter as shown in Figure 1.1.
②Turn 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.)
③When 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 measurements 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
determinethecorrespondingtemperature.
④Increase the power switch setting, first to
6.5, then to 8.0, then to “HIGH”. At each
setting, wait for the cube to reach thermal equilibrium, then repeat the measurements
of step 1 and record your results in the appropriate table.
1
234567
8
LOW HIGH
CAUTION: HOT!
CAUTION
HOT!
THERMISTOR
ModelTD-8554A
(LESLIE'S CUBE)
100W
BULB
MAX.
ON
OFF
Millivoltmeter
Ohmmeter
Figure 1.1 Equipment Setup

6
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
①Place 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?
②Remove 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
(mV)
Sensor
Reading
(mV)
Sensor
Reading
(mV)
Sensor
Reading
(mV)
Ω
°C
Ω
°C
Surface
Black
White
Polished
Aluminum
Dull
Aluminum
Surface
Black
White
Polished
Aluminum
Dull
Aluminum
Surface
Black
White
Polished
Aluminum
Dull
Aluminum
Surface
Black
White
Polished
Aluminum
Dull
Aluminum
Power Setting 5.0 Power Setting 6.5 Power Setting 8.0 Power Setting 10.0

7
012-04695D Thermal Radiation System
Questions (Part 1)
①List the surfaces of the Radiation Cube in order of the amount of radiation emitted. Is the order
independentof temperature?
②It is a general rule that good absorbers of radiation are also good emitters. Are your measure-
ments consistent with this rule? Explain.
Questions (Part 2)
①Do different objects, at approximately the same temperature, emit different amounts of radiation?
②Can 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
①What do your results suggest about the phenomenon of heat loss through windows?
②What do your results suggest about the Greenhouse Effect?

8
Thermal Radiation System 012-04695D
Notes

9
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
Top View
X
Millivoltmeter Meter Stick
Align zero-point of meter stick
with center of filament
Power Supply
(13 V MAX!)
Figure 2.1 Equipment Setup
①Set up 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-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.
②With 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, in order to
determine the contribution from the lamp alone.
③Turn on the power supply to illuminate the lamp. Set the voltage to approximately 10 V.

10
Thermal Radiation System 012-04695D
X Rad 1/X2Rad - Ambient
(cm) (mV) (cm-2) (mV)
2.5
3.0
3.5
4.0
4.5
5.0
6.0
7.0
8.0
9.0
10.0
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
100.0
ä IMPORTANT: Do not let the voltage to the lamp exceed 13 V.
④Adjust 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.
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 Level
(cm) (mV)
10
20
30
40
50
60
70
80
90
100
Table 2.1
Ambient Radiation Level
Average Ambient
Radiation Level =

11
012-04695D Thermal Radiation System
Calculations
①For each value of X, calculate 1/X2. Enter your results in Table 2.2.
②Subtract the Average Ambient Radiation Level from each of your Rad measurements in
Table 2.2. Enter your results in the table.
③On a separate sheet of paper, make a graph of Radiation Level versus Distance from Source,
using columns one and four from Table 2.2. Let the radiation level be the dependent (y) axis.
④If 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
①Which of the two graphs is more linear? Is it linear over the entire range of measurements?
②The 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?
③Is 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?

12
Thermal Radiation System 012-04695D
Notes

13
012-04695D Thermal Radiation System
Experiment 3: Stefan-Boltzmann Law (high temperature)
EQUIPMENT NEEDED:
— Radiation Sensor —Stefan-BoltzmannLamp
—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=σT4;σ=5.6703 x10 –8
W
m2K4
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. The
filament temperature can be determined using the procedure given on pages 3 and 4 of this
manual.
–+
+
–
6 cm
Figure 3.1 Equipment Setup
Voltmeter
Ammeter
Millivoltmeter
Power Supply
(13 V MAX!)

14
Thermal Radiation System 012-04695D
Procedure
ä IMPORTANT: The voltage into the lamp should NEVER exceed 13 V. Higher voltages
will burn out the filament.
①BEFORE TURNING ON THE LAMP, measure Tref , the room temperature in degrees
Kelvin, (K=°C + 273) and Rref , the resistance of the filament of the Stefan-Boltzmann Lamp
at room temperature. Enter your results in the spaces on the following page.
②Set 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.
③Turn 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 ammeter reading, and Rad, the
reading on the millivoltmeter.
ä 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.

15
012-04695D Thermal Radiation System
Data and Calculations
①Calculate R, the resistance of the filament at each of the voltage settings used (R = V/I).
Enter your results in Table 3.1.
②Use 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 T4for each value of T and enter your results in the table.
④*On a separate sheet of paper, construct a graph of Rad versus T4. Use Rad as your dependent
variable (y-axis).
*In place of calculations ①and , 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
①What is the relationship between Rad and T? Does this relationship hold over the entire
range of measurements?
②The 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?
③What 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
Tref (room temperature) = _______ K (K = °C + 273)
Rref (filament resistance at Tref) = ________Ω
V I Rad R T T4
(Volts) (Amps) (mV) (Ohms) (K) (K4)
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

16
Thermal Radiation System 012-04695D
Notes