Robert Cinca - Physics
Part 2.2: Processed Data Tables and Graphs for 6.5V 0.30A Filament Bulb
The relationship was tested experimentally with two different filament bulbs, using
the circuit seen in Figure 1. By varying the resistance in the circuit, I adjusted the
final
current and was
able during
to measure
the surge can
current
times in for
different
The
measurements
taken
this experiment
be seen
Figure
8: final
currents. I recorded all my measurements using a voltage and current data logger,
and data studio (a computer program), which let me plot current against time, thus
Final
Current
Time, T/s
1/(Final Current) 2 ,I -2 /A -2
enabling me to measure the Surge
surge
current
time.
Current
I/A
(±0.005s)
Uncertainty
An excel
to Average
see if the filament
bulb can be Average
effectively Uncertainty
(±0.01A)
Run 1 spreadsheet
Run 2 Run 3 was
Run 4 then
Run used
5
4
0.13 modeled
1.195 as
1.165
1.190
1.173 , radiated by 0.02
59.2
a hot 1.168
body 1.148
radiator
. The power,
the filament is
given by: 9
0.14
0.891 0.888 0.974 0.941 0.924
0.924
0.04
51.0
7
0.16
0.813 0.799 0.853 0.831 0.825
0.824
0.03
39.1
5
0.17
0.755 0.609 0.669 0.698 0.674
0.681
0.07
34.6
4
0.19 (Where
0.530 is 0.556
0.548
0.582
0.492
0.542
0.05
27.7
the emissivity of tungsten, is Stefan-Boltzmann’s constant, is the 3
0.20
0.430 0.441 0.468 0.487 0.444
0.454
0.03
25.0
3
surface
area of the filament, and is the 0.394
temperature of the
filament in Kelvin.
0.21
0.364 0.382 0.455 0.408 0.363
0.05
22.7
2
0.24
0.279 0.334 0.270 0.277 0.354
0.303
0.04
17.4
1
0.26
0.268 0.273 0.298 0.254 0.247
0.268
0.03
14.8
1
0.27
0.201 0.216 0.224 0.265 0.245
0.230
0.03
13.7
1
0.30
0.162 0.222 0.186 0.167 0.161
0.180
0.03
11.1
0.7
0.31
0.167 0.185 0.150 0.152 0.222
0.175
0.04
10.4
0.7
0.32
0.141 0.148 0.150 0.190 0.106
0.147
0.04
9.8
0.6
Figure 8: Data Table of 6.5V 0.3A Filament Bulb
The current values were limited by the precision of the data logger (±0.01A). The
uncertainties of the surge current time were determined by the half range value for
each final current, or limited to ±0.005s by the meter precision.
To calculate the uncertainty of the final column, I used the following formula:
-2
(DI) =
2DI
I 3
For example, using the above formula, to calculate the uncertainty for the value 59.2,
I did: (DI) -2 =2(3) 3 , giving me an answer of 9.10, rounding it to 9 (one
significant figure).
4
“Emissivity”, Higher Level Physics (Hamper, 2009) p298
33
15
5