Title: 3.5 Thermal Radiation
Date Experiment was performed: 23/2/2018
Lab Partners Name: Dylan Loughnane (15152642) Mark Timlin (14165457)
Author of Report: Rebecca Gavin (16153111)
Name of Module: Thermal Physics (PH4042)
Aims:
In this experiment we're trying to show how heat transfer is a mechanism of conduction, convection and radiation. We do this with a two part investigations. First part of the lab will test the stefan-boltzmann constant at high/low temperatures and how different temperatures. The second part of the lab we will investigate how different types of surfaces areas effect emissivity.
Set up/Procedure:
Part 1:
Set up a circuit with the stefan-boltzmann Lamp a power supply
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Then using the radiation sensor to measure the thermal radiation (4 surfaces). Also take notes of the voltage across the cube (voltmeter). Then using the target thermistor resistance at temp of 125 ͦC, 120 ͦC, 115 ͦC etc.(use a fan to cool the leslies cube)
Theory:
Stefan-Boltzmann law is defined as J=ɛσT4
Where T= radiates energy with radiant heat flux σ= 5.67x10-8 Wm-2 K-4 ɛ= (0,1) the ɛ is equal to when 1 when the object is a black body.
In this experiment we are using a sensor that is emitting radiation and we must take into account the corresponding
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0.3 3.68 1.568 2.353 16.24x10-6 705 6.56 -1.56 26.5
0.48 4.57 1.776 2.578 17.74x10-6 758 6.63 -1.2 26.5
0.76 5.65 1.982 2.853 19.69x10-6 823 6.71 -0.73 26.84
1.02 6.59 2.146 3.075 21.22x10-6 875 6.77 -0.27 27.08
1.27 7.57 2.305 3.286 26.67x10-6 824 6.83 0.02 27.3
1.61 8.54 2.450 3.481 24.02x10-6 969 6.88 0.24 27.5
1.96 9.53 2.604 3.662 25.27x10-6 1011 6.92 0.48 27.67
2.35 10.51 2.703 3.834 26.45x10-6 1050 9.96 0.85 27.82
2.75 11.48 2.870 4.001 27.22x10-6 1089 6.99 1.01 29.97
J∞T4=J=aT4 Ln(J)=Ln(a)+4ln(T) Y= c + mx Y= -5.5692 + 0.7225x therefore slope is 0.7225
Results part 2:
Black side of Leslie Cube:
R (Ώ) T(K) Ln(T4-Ta4) Vr (mV) Ln(Vr)
3500 388 23.44 15.61 2.75
4150 382 33.34 14.00 2.64
4901 377 23.26 12.47 2.52
5750 372 23.17 11.15 2.41
6755 367 23.08 10.43 2.34
7707 363 23.0 9.42 2.24
White side of Leslie Cube:
R (Ώ) T(K) Ln(T4-Ta4) Vr (mV) Ln(Vr)
3500 388 23.44 15.46 2.74
4150 382 33.34 13.567 2.64
4901 377 23.26 12.8 2.55
5750 372 23.17 11.55 2.45
6755 367 23.08 10.64 2.36
7707 363 23.0 9.86 2.24
Dull side of Leslie Cube:
R (Ώ) T(K) Ln(T4-Ta4) Vr (mV) Ln(Vr)
3500 388 23.44 4.78 1.56
4150 382 33.34 4.77