Laboratory work No.: 16
INVESTIGATION OF THERMAL RADIATION AND MEASURING TEMPERATURE BY
OPTICAL PYROMETER
Purpose: to measure the temperature of an incandescent body and calculate the Stefan-Boltzmann constant
Equipment: Pyrometer, heating lamp, voltmeter, ampermeter, power source.
Table:
Nr.
1
2
3
4
5
I,A
4,80
4,45
4,70
3,50
5,35
U,V
7,30
6,55
5,60
4,65
7,00
T,⁰C
1200
1120
1040
920
1340
Tr,K
1473
1393
1313
1193
1613
T,K
1504
1422
1338
1215
1649
Calculations performed according given table durring the experiment:
1)
2)
3)
4)
5)
Tx1= 1473/1400*1429=1504
Tx2=1393/1400*1429=1422
Tx3=1313/1300*1325=1338
Tx4=1193/1200*1222=1215
Tx5=1613/1600*1636=1482
T0= 21⁰C =294 K (temperature of environment)
Data given:
S=7*10^(-5) m2
A=0,85
Counting Stefan-Boltzmann const.:
By using the formula given
σ1
σ2
σ3
σ4
σ5
σ avg
1,15*10^(-8)
1,2*10^(-8)
1,38*10^(-8)
1,26*10^(-8)
0,85*10^(-8)
1,168*10^(-8)
Conclusions
As it is possible to see the received constant is quite a lot smaller than theoretical one. It is possible to
conclude that the deviation of the value could be affected due to wrong indications of temperature. It was
difficult to compare the intesity of the wires seen through the ocular as the overlapping wire parts were
unclean and the image was not with sharp edges.