Thermodynamics
> Heat and the First Law > Radiation
DCS#
6B40.55
STEFAN
BOLTZMANN
LAW
APPARATUS
Stefan Boltzmann lamp
214-02-D5
Lambda 0-7 A DC power
supply
202-16-B
two digital multimeters
214-01-B5
thermopile
214-02-D5
foam heat shield
214-02-D5
video camera
202-09-C
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.
Use Keithley 197 DMM to measure filament resistance at room
temperature.
Use temperatures above 1500 K to
show the
T4 dependence. At lower temperatures,
absorption of
infrared
radiation by the glass lamp bulb affects results.
