• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5
6. 6
6
7. 7
7

# The aim of my Hot Water Tap Thermometer is to create an electronic thermometer that will accurately measure the Hot Water Tap's water temperature.

Extracts from this document...

Introduction

Hot Water Tap Thermometer

Context

It can be dangerous when placing your hand under a hot water tap, as you can never tell if the water is going to be too hot or not. The water can cause some scalding to the skin. I have researched and found that the average hot water temp is 50 oc. And that the skin can be scaled above 60 oc.

Aim

The aim of my Hot Water Tap Thermometer is to create an electronic thermometer that will accurately measure the Hot Water Tap’s water temperature. I am going to use an electronic circuit to measure the temperature and use the voltage to calculate the temperature.

Theory of Semi-Conductors

At ordinary temperatures, they only have a few free electrons. As the temperature increases more electrons are liberated

In insulators the energy gap between the two bands is large, so they have few electrons in the conductor band (this means no conduction can happen.) in semi-conductors energy bands close to the conduction bands are created. When heated enough energy is given to electrons to move the conduction band and the current increases.

Middle

60

0.65

0.62

0.66

70

0.53

0.51

0.57

Supply voltage = 3.03 volts

Resistance = 500 ohm’s

##### Things to change
• I will use the higher supply voltage of 5 volts to make my data more accurate
• I will increase the resistance of the resistor in series with the thermister to 10’000 ohm’s (10 K ohm’s) this should increase the resolution of my results.
• I will make sure that the thermistor is placed at the top of the beaker containing the water so that the highest temp of the water is recorded.
• I will repeat each temperature 5 times so that I will have a clearer average and any strange results can be noticed.
• I will measure between 30 and 65 oc and will increase the temperature in multiples of 5, i.e. 30,35,40,45…etc

Circuit Diagram

Safety

I will follow the following safety point so that I do not injure others or myself.

• I will make sure that my circuit is safe before I connect the power to it.
• I will be careful when using the hot water, so that I do not scald my skin
• I will keep the voltage of the power pack low so that I can not be electrocuted
• Make sure that the water I am using does not connect with the electrics

Fair test

It will be very important during my experiment that I keep the conditions of the experiment the same so that my results are correct.

Below is a list of points that helped my test to be fair:

• I used the same voltage throughout the experiment
• I made sure that the thermistor was at the same depth in the water for each reading.
• I made sure that the resistance of the resistor in the series circuit remained the same.
• I will use the same power amount of water for each reading

Conclusion

## The average Change (Sensitivity) is = 0.023371 per degree

Resolution

Resolution is the smallest change that the circuit can detect. This determines how accurate the reading is.

## 50oC = 0.60 v       52 oC = 0.56

Response time

Response time is the time it takes for my circuit to respond to the change in temperature then give the output. I had a lot of difficulty calculating the response time of my circuit. This was because the response time of my circuit was much quicker than any thermometer I had. So it was detecting the change almost instantly, where as the glass thermometer was taking up to a few seconds. This meant that I had nothing to compare my circuit’s readings to.

### Conclusion

Now that I have finished my experiment and collected and analysed my results I will now sum up what I have recorded. My results have shown that I predicted correctly and that the temperature is inversely proportional to the voltage across the thermistor.

This proves the theory that a thermistor is a semi-conductor, and that it behaves different from conductors. When the temperature of the thermistor increases, the current increases and the resistance drops.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related AS and A Level Electrical & Thermal Physics essays

1. ## Investigate how the temperature affects the resistance of a thermistor.

After all equipment is set up and the test tube with the thermistor has been put inside the beaker of water I will put ice in the beaker until the temperature is at 100C. I will measure this temperature using a thermometer will a scale of 10C that goes up

2. ## An experiment to measure the specific heat capacity of water

At this point, we weighed the beaker and water again. Beaker plus warm water = 295.89g Difference in water from start to end of experiment = -0.37g No steam or evaporation was noticed. We felt that it was therefore reasonable to assume that the majority of this missing water was probably on the removed coil.

1. ## I am going to investigate what the resistivity is of a pencil lead. ...

Other than this one there are no obvious anomalies. This is because I can make the voltage almost exact and cut down on other variables that would have affected the result. I was expecting the shape of the graph to be a straight line passing through (0,0)

2. ## Characteristics of Ohmic and non-Ohmic Conductors.

From the results, I can see that Current increases with Voltage for all the graphs. But the way in which it increases is different. Any difference in reading may be due to some error, which I will account for in evaluation.

1. ## The aim of my investigation is to determine the specific heat capacity of aluminium.

Heat is transferred relatively slowly from the heating filament to the aluminium block through convection current within the air, which is in the space between the filament and the block. Conduction then takes place, which transfers the heat through out the block .

2. ## Sensors cwk. The aim of this coursework is to construct a potential divider circuit ...

This is because when the object is twice as far away, the area of the object becomes 4 times as big, therefore the energy needs to spread over four times the area; thus 1/4 the light intensity. This relationship can best be understood by looking at a diagram, as below;

1. ## Using an LDR to detect the intensity of plane polarised light allowed through a ...

* Or, I could get a formula of the internet, and then use my data to comment on the effectiveness of my sensor. I have chosen to do the latter. As such, on http://lsn.curtin.edu.au/tlf/tlf1997/swan.html (a website intended to suggest to university lecturers how to include the subject of polarisation), I

2. ## Aim To build and test a temperature sensor and analysing its suitability as ...

However there are some thermistors which are not suitable for this type of temperature measurement. Many PTC thermistors are of switching type, which means that their resistance rises suddenly at a certain critical temperature. The barium titanate thermistor does this but also changes between PTC and NTC thermistors at high and low temperatures.

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to