Exploring the characteristics of a sensor

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Exploring the characteristics of a sensor

AIM:

The aim of my experiment is to measure the resistance of a thermistor at temperatures which are acceptable by the human body. I can then use this information to create a sensor that can be placed in a bath to record the temperature. This will be beneficial to people who cannot feel the temperature of bath water such as a person who has suffered from a stroke.

RESEARCH

To be able to do my experiment successfully I needed to find out a suitable temperature range to test on.  I found out that the human body tolerates temperatures from 25˚C to 45˚C.

I also decided to research thermistors. There are two kinds of thermistors; these depend on the sign of the resistance. If the resistance is positive, the resistance increases with the temperature and is called positive temperature coefficient (PTC) thermistor. If the sign is negative, the resistance decreases as the temperature increases. This is called a negative temperature coefficient (NTC) thermistor.  

VARIABLES

For my experiment to be a success I must make it a fair test. To do this there are some factors I need to keep the same and some I need to change. The main factor which will be changed is the temperature of the water so I can determine the resistance of the different temperatures. However, there are a few things which I will keep the same. I will need to keep the thermistor and resistor I use the same. This will ensure that my readings are more accurate. I will also keep the amount of water I use the same.

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METHOD

To be able to do my experiment I will carry out the following steps

  1. I will set up the equipment in the equipment as shown in the diagram
  2. Before I start the experiment I will cover the thermistor with cling film so it does not become damaged in the water
  3. I will make sure the water I am using is at the correct temperature I need
  4. When this is all ready I will put the thermistor into the beaker of water and run the jockey up and down the wire on the meter bridge till ...

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