• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Measuring the temperature in a greenhouse using a thermistor.

Extracts from this document...

Introduction

Measuring the temperature in a greenhouse using a thermistor

Aim

I have decided to measure the temperature of a greenhouse using a thermistor in a potential divider circuit. A thermistor is a temperature sensor whose resistance will increase or decrease with temperature change depending on what type of resistor.

An alternative for this experiment could have been measuring light levels in a greenhouse using an LDR. A light sensor in a green house could tell you when and where in the greenhouse the most intense sunlight is, which you could you use to aid your growing skills.

I decided to design a temperature sensor for a greenhouse using a thermistor, as temperature can be critical in growing plants especially if it gets too hot or too cold.

I have decided to use a 100K NTC precision thermistor as it can measure a range of temps from – 50 to 110 degrees C, and in Britain temperature range from around –10 to 50 degrees C, so my thermistor will cover these ranges.

...read more.

Middle

To measure response time I will up 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. 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.

To measure drift I will put my thermistor at room temperature and measure the output voltage every 10 seconds for one minute. Here I am looking for any anomalous results before the output voltage is stable.

Safety precautions will be taken into account throughout the experiment and goggles will be worn, hair tied back and apparatus set up carefully.

Results

The sensitivity of a measuring system is the ratio of change of output to change of input.

...read more.

Conclusion

When I was measuring drift it did take 30 seconds to reach a stable reading but in the situation for which I want my sensor that sort of time is appropriate as extremely accurate readings are not necessary. The fluctuations were also very slight so it wouldnt effect results.

When measuring response time it took longer to go from cold to hot than it did to go hot to cold. It was a lot more responsive to the change to cold as also it is with sensitivity which will is good for my sensor as I need to know sooner when cold temperatures are coming.

After analysing certain aspects of my sensor I believe it to be it to be good enough to be used in measuring temperatures in a greenhouse as its sensitivity is accurate enough and drift and response time are also quick enough. Although this is not the most accurate sensor for this job it is good enough another one may be used if more accurate work is being done.

...read more.

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

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

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

    because the temperature in the component is not that close to the temperature of the water of the air surrounding the thermistor. Another method I thought of was to heat the water in a beaker of water but this method would definitely not of been that effective because water conducts

  2. Investigate the relationship between temperature and resistance in a thermistor.

    that, as in a wire, the lattice atoms vibrate faster and collide with the flow of charge ( which is the flow of free electrons) slowing it down and reducing the current. And b) that because it is a semi conductor the outer electrons get more energy as it is

  1. Making, Calibrating and Testing a Sensor

    there could be a cloud cover, the disadvantage of this is that the results may not be comparable because they will have different values dependant on the lights intensity. However, this was identified early into the experiment and a lamp was used instead because its intensity can be controlled and

  2. Investigation On The Resistivity Of Apples. Since we are measuring the resistance of an ...

    � 30.4 2 170.0 170.2 169.0 3 176.0 190.0 178.2 Modifications The results we obtained were non-precise and irregular, so the graph plotted is not linear. From the graph before it is obvious that there is little correlation and the error uncertainty associated with the results is very large.

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

    The most significant was the sensitivity of the device. The sensitivity of a measuring system is the ratio of change of output to change in input. The problem with my device was that the output voltage did not change for the first 150cm3 of water added into the beaker; however any addition of water after this caused a change in output given there was a change in input.

  2. physics sensor coursework

    R1 = (4.39 � 1500)/ (10 - 4.39) R1 = 1173.80 ? Although the graphs indicate my prediction, of voltage output deceasing with increasing light intensity, is correct, I found many complications throughout the preliminary experiments. One, is the difficultly with changing the light intensity using a book or a material like that.

  1. Free essay

    The Relationship Between the Input and Output of an LDR

    Heavy equipment (e.g. the powerpack) could fall and do serious damage to a person's foot. Also, wires could trip people up, this is in the case of the longer thicker wire that will be connected to the mains supply (the powerpack's wire).

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

    The reason that I chose an LDR is because, most importantly, it is a passive sensor and this means that I am able to change its sensitivity by using whetstone networks, amplifiers or by inserting it into a potential divider.

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