Does the length of a wire affect the resistance? -- A* - page 1
Keywords: Physics length of wire resistance
By georgie1 on 31/12/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 1 of 6 pages: 1 2 3 4 5 6
Does the length of a wire affect the resistance?
Investigation to find out how the length of a constantan wire affects the resistance when it is varied
The aim of my experiment is to discover what factors affect the resistance of a wire in an electrical circuit. The output variable that I shall be recording is the resistance, using the formula of:
Resistance R = Potential Difference across the wire (Voltage) V
Current through the wire (Amps) I
The possible input variables that I could have changed are temperature, diameter, material and length. I have chosen to vary the length of resistance wire as my input variable because it is the easiest to monitor and measure in comparison with the other options. It will give me more precise results because I am confident in how to complete the experiment properly. If I was to change temperature or material, the results would be difficult to collect accurately and therefore they may not show significant patterns in my results. As a result, the factors that I will control are:
• Diameter of the wire (32 SWG, 0.29mm). [See Preliminary Experiment for justification].
• Temperature of the wire. To keep the temperature consistent, I am going to use the circuits for the shortest time possible to ensure that the wire does not heat and therefore cause the nuclei to vibrate more strongly and create more collisions. This would result in an increase of resistance. In the same way, I am also going to ensure that the temperature of the room does not fall too low, as this would allow the electrons to move faster past the positive ions. This means that they wouldn’t lose much energy and therefore could move faster, decreasing the resistance. As a result, I am going to maintain the experiment at room temperature [approximately 26˚c].
• Material of the wire. So that the resistance is not affected by another factor, the material will be consistent so that all materials will have the same conduction.
• Tension of the wire. To keep the tension consistent, I am going to keep it straight and stretched to the usual shape of the wire, so that the nuclei are not more/less compact.
To ensure that my investigation is thoroughly reliable, I am going to collect 3 sets of results so that I can clearly identify any obvious anomalies, and can calculate averages to find a strong set of accurate results. I am going to measure
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