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# My aim is to find the change in resistance as a current is passed through different lengths of wire as measured by ohms law (R=V/I). I kept all the other variables constant, E.g. Diameter of wire and Voltage remained constant.

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Introduction

AIM.

My aim is to find the change in resistance as a current is passed through different lengths of wire as measured by ohms law (R=V/I). I kept all the other variables constant, E.g. Diameter of wire and Voltage remained constant.

VARIABLES.

• Temperature – an increase in temperature results in greater movement of electrons through the wire.
• Length of wire – the longer the wire the greater distance the electrons have to travel.
• Type of wire – some wires have more impurities that increase the resistance of current through them.
• Diameter of wire – a thicker wire provides a greater area for electrons to pass through.
• Number of strands in wire – more strands will increase the electron flow.
• Density of material – higher density means more resistance because there is less space between atoms for electrons to flow.
• Voltage & Current – an increase in voltage and current increases the movement of electrons through the wire.

HYPOTHESIS.

I predict that as the length of the wire increases, the resistance will increase as measured by the current and voltage (Ohms law).

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Resistance was calculated, as above, by the formula: R = V(Ohms Law)

I

These were the results:

 RESISTANCE MEASURED                              (Ohms) Length of wire (cm)

Conclusion

I would ensure that the quality of the wire was the same through out so that the impurities did not affect my results. This could be done by ensuring the wires for the experiment were obtained from the same manufacturing batch.

As well as making these modifications I would also improve my investigation by testing the same wire but different diameters of that wire. I would do this to expand on my investigation.

The experiment could have also been affected by other factors; for example, the wire could have been heated up during the day by the sun or any other form of heat. This would have affected the movement of the atoms within the wire.

Fig.2 shows a few anomalies. The readings of 15cm through to 30cm (15,20,25 & 30cm) and also 45cm are all above or below the line of best fit. This could be because the ammeter readings were incorrect.

In developing my investigation further, I would test how the temperature of the wire would affect the resistance measured. I would vary both the length and temperature of the wire as this would also vary the surface areas of the wire, which could affect the results.

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