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Investigate the relationship between length of a wire and its consequential resistance.

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To investigate the relationship between length of a wire and its consequential resistance.


In metals, current is the flow of electrons. In each of these molecules, a few of the electrons can move which allows current to pass along it. When we put a battery in a circuit it makes the current flow in one direction round the circuit from - to + (negative to positive). When these electrons reach the positive terminal again, they are given a “boost” and continue around the circuit.

        All metals in the wires, and components, cause resistance, which slows down the speed of the electrons. Resistance is found by doing the Voltage over the Current. This resistance is based on several things. Length, which I will be investigating during this experiment, affects resistance because the longer the wire is, the more electrons there are to slow down the electrons increasing the resistance. This should be directly proportional because twice the length is twice the number of atoms, which means twice the resistance. I will be hoping to prove this in the main experiment.

        Another factor affecting resistance is temperature. When we have a high

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100 cm








From these results I can easily establish which wire I will be using. I will use the thick Constantine wire. This is because it has the widest range of results. 0.64 to 1.17 is the biggest difference of all the voltages as was 0.62 to 0.24 in the current so it is the obvious selection.

Main Experiment


1 Thick Constantine wire

1 Voltmeter

1 Ammeter

2 Crocodile clips

1 Power box

6 wires

1 Ruler

Masking Tape

Heatproof mat


These are the variables in the main experiment. Length.

These are the constants. Voltage supplied, Thickness, cross-sectional area, Temperature, and Material.



Planned Method

  1. Set up the circuit as shown in the diagram.
  2. The length of wire is taped tightly to the 100cm ruler.
  3. Crocodile clips are put at the 0cm mark and 20cm mark
  4. A reading is taken of the current and voltage.
  5. The current is turned off quickly to prevent and possible temperature.
  6. This is repeated twice to ensure accurate results.
  7. This is repeated until we reach 100cm at 10cm intervals (20,30,40…)
  8. The results taken are turned into 3 resistances for each length and an average is found for the 3 tests.
  9. This is finally drawn up on a graph with a straight line.


        There are a few points of safety to observe when carrying out the experiment.

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I was fortunate to have no anomalies in my experiment. An anomaly would be where 1 result is a long way out. On my graph, the points were all on the line (or very close to) so there were no obvious anomalies. Generally, none were out by more than 0.05 ohms, which is a very low amount and is probably due to the equipment not being accurate enough. With better equipment, these would probably no longer be there as the resistance would be more precise.

All in all, I would say the experiment went well. I was able to obtain results quickly and accurately. Also, I believe I performed the experiment in a safe manner using the guidelines given. I was able to establish how length and resistance are directly proportional to each other which was that aim, so this was a good point.

There were a few things I could have improved on. One major thing was that I did not start my coursework as early as I could have. I f I started earlier, it would have been more polished and detailed. In the future I should aim to start earlier to spread the work over the entire time.

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