Temperature coefficient resistance of a thermistor.

* Two lengths of wire

* A thermometer

* A multi-meter set to measure resistance

Method:

First fill the beaker with water and place over the Bunsen (on a tripod and gauze) and place in it the thermometer and thermister (and shown in the diagram below). Connect the thermistor to a multi-meter and set it to measure the resistance. As the water is heated record the temperature and resistance at different intervals.

Results table:

temperature

resistance

temperature

resistance

8

571

69

29

21

520

71

19

24

473

74

10

27

448

77

05

30

404

79

96

32

365

83

87

35

321

84

84

37

297

85

80

40

282

86

75

42

263

89

70

47

242

91

69

51

216

92

62

53

86

94

60

56

75

95

58

60

64

97

55

62

51

99

53

65

44

00

51

68

38

Graph:

Conclusion and evaluation:

From the graph it is possible to see that the resistance of the thermistor decreases as the temperature increases, at a lower temperature the resistance is up to nearly 600ohms and a much higher temperature the resistance has dropped to only 50ohms. This means that the temperature of a thermistor is proportional to the resistance.

As there where anomalies in the graph the results might have been inaccurate, these are some of the ways that I thought the experiment and the results could have been inaccurate and how I would have improved on these points in the future if I were to do this experiment again.

* The thermometer that I used was graduated only to one degree Celsius so accurate temperature was not possible to take; I could have made the measurement more accurate if I had used a thermometer that was graduated to 1/2 a degree or less.

* The way that I performed the experiment was to place the thermistor in a beaker of water and heat from beneath with a Bunsen burner, and then as I read the temperature I would also look at the multi-meter to look and see what the resistance was. The problem with performing an experiment like this was the temperature was constantly changing and it was changing too quickly, this meant that if read the temperature and recorded it, by the time I read the multi-meter to find out the resistance it had changed because the temperature was constantly rising. The way that I could overcome this problem in the future would be to use water baths set to a certain temperature and take several readings in order to gain an average and then move on the next temperature. Would mean that the temperature would not me changing as much and the resistance reading would be mush more accurate.

* When I had the thermistor in the water bath (beaker) I did not stir the water, this meant that the water was different temperature in different parts of the water, meaning the temperature of where the thermistor was in the beaker could have been different to the temperature of where the thermometer was in the beakers, meaning the resistance reading that I took was not the correct one for the temperature that show up on the thermometer, this would also have made my results inaccurate.