I chose to do my sensors project about sliding potentiometers because they are very common in every day life, and I thought it may be interesting to discover how they work.

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Physics coursework

Introduction

I chose to do my sensors project about sliding potentiometers because they are very common in every day life, and I thought it may be interesting to discover how they work. There are potentiometers on lots of everyday household appliances, sliding and rotary potentiometer on hi-fis to change the volume or tuning, washing machines and dishwashers to change settings and other electrical equipment and machine. As the world becomes more computer reliant sensors will be used more often, especially potentiometers as they are easy to operate. Rotary and sliding potentiometers both work in a similar fashion. As the slider gets moved along, the voltage increases as the potential difference changes. A rotary potentiometer works the same way, but is twisted round, so rather than measuring displacement, degrees are considered. I will take this simple idea and look into true values and patterns.

Plan

Fig 1.  Circuit diagram of  the circuit to be built.(Not to scale)

I am going to build the diagram as shown above and slide the potentiometer along and see what the different readings of the voltmeter are.

The equipment I shall be using is:

     

  • Wires x 4
  • A 59mm sliding potentiometer (5kB)
  • A digital voltmeter, Rapid 212 DMM. Reading error: 0.005V
  • 30cm Ruler. Accuracy: 0.5mm
  • Stopwatch, Unilab Accuracy: 0.005 secs
  • Power Pack (1kWIN L.V power supply (J0032)). Reading error 0.005V

I have chosen to use a power pack rather than a battery pack as I can guarantee that the voltage will be constant and not drained, as would happen with a battery pack.

Safety is a very important factor to consider as potentiometers are used by many people so safety is paramount. Safety is important in my experiment so I don’t get injured, and either do my classmates. I have considered safety by making sure that all wires are secure and bare wires are not exposed, not making a short circuit as that could make my equipment hot and dangerous to handle and making sure that all my equipment is connected correctly so the equipment is used correctly and safely, like the manufacturers intended. Safety was considered all the way through my experiments.

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Theory

        To predict what results I will get for my experiment the theory of how a sliding potentiometer must be considered. A potentiometer is simply a potential divider. The position of the slider decides what the resistance is either side of it, like splitting up the potentiometer into two resistors. Moving the slider on a resistor taps off a potential difference proportional to its displacement. If we think of it in this way, the theory behind it is fairly easy to comprehend.

Fig 2. Potentiometer as two resistors.

In this diagram the voltage ...

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