Thermodynamics > Heat and the First Law > Radiation DCS# 6B40.55
STEFAN BOLTZMANN LAW
 stefan boltzmann setup
APPARATUS
Stefan Boltzmann lamp 214-02-D5
Lambda 0-7 A DC power supply 201-16-B
two digital multimeters 214-01-B5
thermopile 214-02-D5
foam heat shield 214-02-D5
video camera 202
 
DESCRIPTION
Plot thermopile voltage vs. filament temperature to show that radiant energy is proportional to T4.  Use the foam piece to shield the thermopile between readings.

NOTES

Do not exceed 13 V to the lamp filament.
Determine temperatures for various filament voltages prior to demo.
data for stefan boltzmann lamp, 203-1-B5-10:
R (T=25 C) = 0.350 Ω as measured with Keithley 197 DMM
V(V)
T (K)
5
1550
6
1690
7
1800
8
1880
9
1980
10
2070
11
2140
12
2230

Use temperatures above 1500 K to show the T4 dependence.  At lower temperatures, absorption of infrared radiation by the glass lamp bulb affects results.
 
 
REFERENCE

Pasco Thermal Radiation System instruction manual