The Effects of Temperature on Resistance.
Extracts from this document...
Introduction
James O'Farrell Page 5/2/2007
The Effects of Temperature on Resistance
The Effects of Temperature on Resistance
Aims
To investigate the effects of temperature on resistance.
Background Research
Apparatus
Diagram
The Variables
The Measured Variables
Accuracy
Data Range
Proposed Data Processing
Results
Raw Data
Processed Data
Graph of Processed Results
Analysis or Results
Planning
Aims
To investigate the effects of temperature on resistance.
Background Research
Form background reading and research I have discovered that for most materials that conduct electricity there is some degree of variation of resistance with temperature. There is a set equation governing this change as follows;
Rθ= R0(1+αθ) = R0 + αR0θ
Where
Rθ= Resistance at Temperature θ
R0 = Resistance at 0°C
α = The temperature coefficient of resistance.
As we will see after we have done the experiment the temperature coefficient will turn out to be negative as I am sing a N.T.C. Thermistor
Apparatus
- Negative temperature coefficient thermistor.
- Voltage meter (V)
- Ammeter (A)
- Power Pack (Low voltage DC)
- Freezer
- Heater
- Beaker
- Thermometer
Diagram
The Variables
In this section I will look at all the possible variables and decide which ones should be varied in order to obtain results showing the effect of temperature on resistance.
Middle
16
1.94
0.216
1.96
0.216
34
1.66
0.308
1.66
0.309
39
1.48
0.307
1.48
0.310
48
1.35
0.342
1.35
0.346
57
1.21
0.372
1.22
0.371
66
1.15
0.454
1.17
0.447
77
1.01
0.506
1.02
0.489
83
0.90
0.474
0.88
0.465
Processed Data
Temp | Set1 | Resistance = | Set 2 | Resistance = | Average | ||
+/- 0.5°C | Voltage (V) | Current (A) | V/I (Ω) | Voltage (V) |
Conclusion
We can work out the temperature coefficient at using the equation and taking an average of all the results.
Rθ= R0(1+αθ) = R0 + αR0θ
Temp | Average | Temperature |
R (Ω) | Coefficient | |
0 | 17.3 | ∞ |
11 | 10.8 | -0.0339 |
16 | 9 | -0.0298 |
34 | 5.4 | -0.0202 |
39 | 4.8 | -0.0185 |
48 | 3.9 | -0.0161 |
57 | 3.3 | -0.0142 |
66 | 2.6 | -0.0129 |
77 | 2 | -0.0115 |
83 | 1.9 | -0.0107 |
As we can see from the graph above the temperature coefficient is indeed negative, but it is not a straight line and therefore not constant. This can be explained by the fact that the thermistor itself dose not have a constant rate of change but instead it has a range depending on the temperature.
One conclusion that can be drawn from the data that we have obtained it that there is a distinct change in resistance wit temperature. This can be seen in the first graph, as the temperature rises the resistance falls (NTC).
In further investigation I would like to investigate resistance change and temperature for different components. Also I would like to look at the heating effect on resistors and other components as I think this ma have had some affect on the results.
This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.
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