PASCO TD-8497 Solar Constant - Manual (Page 7)

Solar Constant Model No. TD-8497
6 ®
Suggested Experiment: Finding the Solar Constant
Theory:
Q=mc T (1),
where Q=Thermal Energy added to the cylinder,
m=mass of the cylinder,
c=specific heat of the cylinder,
T=change in cylinder temperature
where I=intensity of sunlight (Solar Constant), A=cross-sectional area of the cylinder (area of
the shadow), and t=time.
Combining equations (1) and (2) yields
where is the cylinder’s rate of temperature change and also the slope of the T vs. t
graph.
Procedure
1. Follow the “Setup Procedure” on pages 4-5. Place the white, silver, and small aluminum
(lighter weight), black cylinder each on a separate stainless steel temp. probe. If using the
Quad Temperature Sensor, use a fourth temperature probe to measure ambient temperature.
Otherwise, record the value of the outside ambient temperature with a standard thermometer.
Make sure to start with the cylinders colder than ambient temperature (See “Experiment
Tips” on page 5).
Equipment Required:
Solar Constant Set (TD-8497) (3) Stainless Steel Temperature Probes
(PS-2153 or CI-6605))
Temperature Sensors: (1) PS-2143 or
(3) PS-2125 or (3) PS-2146 or (3) CI-
6527A Computer interface (PASPORT or
ScienceWorkshop)
DataStudio software Standard Thermometer or Fast Response
Temperature Probe (PS-2135)
∆
∆
I
Q t
⁄
A
---------- =
(2),
I
mc ∆
T
t
--------  
 
A
---------------------- = (3),
T t
⁄ ∆ ∆