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# Does the length of a wire affect its resistance?

Extracts from this document...

Introduction

10/05/2007

Does the length of a wire affect its resistance?

Introduction

In this investigation, what I intend to do is: Perform an experiment whereby, I am testing if the length of a wire increases its resistance. One way in which I intend to do this is record results from a set scale of 10cm and then use these results to draw up a simple graph/series of graphs. I hope that my investigation will prove my theory of length increasing the resistance of a wire, as I believe that the amount of resistive atoms will increase in parallel with mass.

This will cause resistance to increase because as the amount of resistive atoms increases, it means that there will be more of them that the electrons have to pass through so as the circuit can flow.

In this investigation I am going to try and find out whether or not, the length of a wire has any sort of affect on its resistance.

I intend on doing this by using the knowledge I possess prior to this investigation. This knowledge includes such things as: -

• Current flowing through a metal wire is proportional to the potential difference across it. [Providing that temperature is constant]. This is known as ohm’s law.
• The greater the resistance, the more voltage is needed.
• Resistance is calculated by multiplying potential difference across wire in volts, by current through the wire. [R = V x I].

I have selected particular equipment for carrying out my investigation. I have also produced to a method to help me keep the investigation fair, and constant throughout.

The equipment I have chosen to use is:

• A wooden plank with one nail at both end and wire running from end-to-end.
• One ammeter and one voltmeter.
• One power pack. [From preliminary work].
• One batter to supply power.
• A metre ruler for measuring distance of the wire.
• Wire and crocodile clips to connect the circuit.

Middle

Preliminary Work

For my preliminary work, I was trying to see the same thing as in this For investigation, which is, does the length of a wire have an affect on it’s resistance and I was also seeing whether or not the equipment I chosen to use would be able to do the investigation properly.

The equipment I chose to use was:

• A wooden plank with one nail at both end and wire running from end-to-end.
• One ammeter and one voltmeter.
• One power pack [AC]
• A metre ruler for measuring distance of the wire.
• Wire and crocodile clips to connect the circuit.

After carrying out my preliminary work, I decided that using a power pack was not reliable enough. I then had to think of what I could use as a new power source, which would be reliable and help me to collect a fair reading. I decided to change my power source to a battery pack [DC] as it would give a fairer reading for my results and lower the chance of collect anomalous data.

Observation

To make sure I get fair results I intend to collect them in a safe and secure manner. I will also use a chosen range for my results. The range will be ten centimetres per reading. I will use three wires for this experiment.

Conclusion

The ways in which my investigation could have been improved would lie in the method. I say this because, my method could have been slightly more defined, and reduce my scale for readings taken to a five-centimetre scale rather than the original 10 cm used for the investigation. That would have enabled me to collect clearer results, as my range would be wider, enabling the results to be fairer and an easier to work out average. I do still believe however, that my method was of enough use to me for conducting my investigation and being able to draw a meaningful conclusion from the results, which I gained in the process. My theory from my introduction was after all proved correct and I did manage to prove that resistance increases with the length of a wire in a circuit. This increase was due to a build up of resistive atoms inside the wire in parallel with the increase of mass. If I were to conduct this experiment again, the main area I would focus on changing rather than my scale would be to try to be more precise in where I took my readings from, and try to keep all readings from the same distance away from the crocodile clips.

Matthew Cave 11LNS – Science Coursework

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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