There is no constant value for the sensitivity of the thermistor in this experiment because the graph produced is a curve rather than a straight line. This means that the gradient is constantly changing and as the gradient changes, sensitivity is altered. The result is that different points on the graph have different values for sensitivity. But it can be estimated by drawing a tangent to the curve and finding the gradient of this. To measure response time I will have two beakers, one at a hot temperature and the other at a cold temperature.
I will then place the thermistor into the cold beaker, until it reaches a stable output voltage, then I will put it in the hot beaker and time how long it takes for the thermistor reach a stable output voltage in the hot beaker. I will then repeat this going from hot to cold. To make this easier to detect, I used an oscilloscope. Here I will be looking for speed in reaching a stable result and also differences in going from cold to hot and hot to cold.
My average response time is found by dividing the time taken to respond by the difference in temperatures. So mine was = 31ms. Applications of the System – This system has a wide range of applications. It could be used to detect atmospheric temperature, to detect the temperature of liquids, as a clinical thermometer to detect the temperature of people. I could also be used to effectively compare a range of temperatures. It could also be used to determine resistance since temperature is proportional to resistance.
However for this function it is necessary to produce another conversion table to convert the readings in volts to resistance in ohms. Evaluation – The results of this experiment are reasonably accurate because there are few factors that affect it and they tend to remain fairly constant throughout the experiment for example the impurities present in the water and the prevailing atmospheric pressure could affect the boiling point of the water though this is relatively insignificant.
The readings in this experiment are accurate to one decimal point and readings are repeated to reduce the effect of random error and to eliminate erratic error. It is always better to take the average of two or more readings because then we increase the degree of accuracy and precision and what we get is closer to the truth. I do not know precisely the percentage error present in the readings but I would guess that the error should not be more than i?? 1. 2%. The instruments used limit the accuracy.
We only know what the Multimeter tells us and this is to 1 decimal place and is most probably an approximation of the actual value. For example a reading of 4. 14236567555 would be rounded up to 4. 1 to one decimal place and the percentage error in this is about 1%, which is within the limits of experimental error. Safety – The issue of safety is very important in any experiment. In this experiment there is no really serious risk. However even minor concerns cannot be overlooked.