# Resistance Of A Wire Coursework Results Table

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Overall, my results are very consistent with my predictions. Most of the data points were on, or very close to, the line of best fit. There are a few data points that are farther away from the line of best fit than the others, but they are still consistent with the general trend. There are no anomalous results that I would consider to be far away from the line of best fit.

There are possible sources of error that might have led to inconsistent results, such as a kink in the wire. This would have prevented the area of the wire from remaining constant and would have affected my results. However, I made sure that the wire remained straight throughout the experiment.

I think that the range of my results was sufficient enough for me to draw a valid conclusion about how the length of the wire affected the resistance. This was because I could plot a graph and show the general trend.

I think that the pattern/general trend would continue beyond the range of values I used. However, I think that unless I had specialist equipment the results would be distorted because the wire would eventually get very hot. Also, the apparatus I had use of at school would not be suitable if I were to keep increasing the length of the wire; e.g., in a classroom environment I could not increase the length to more than 150cm because of safety concerns as well as space constraints.

I think my method could have been improved to produce results that were even more consistent. I could have considered using a new piece of wire each time in order to regulate the temperature more stringently. Using the same piece of wire throughout the experiment meant its temperature rose slightly over time, which may have affected my results. However, using new pieces of wire each time would have been too impractical and time-consuming in the context of this lesson. Overall, I think my method was sufficient to obtain reliable results.

To support my prediction and conclusion, I could do further experiments. For example, I could use different types of wire instead of using only nichrome. I could also consider using different cross-sectional areas of wires or even change the temperature of the wires deliberately and see how manipulating these variables affect the resistance of the wire.

Resistance of a conductor depends on the length, cross section and material of the conductor:

$R = \rho\frac{l}{S},\tag{1}$

where ρ is the electrical resistivity of the conductor, l is its length and S its cross section.

Electrical resistivity (also known as just resistivity) of a conductor made from a particular material can be found in The Handbook of Chemistry and Physics. Among the best conductors belong e.g. silver, copper, gold, etc. Bad conductors are e.g. Kanthal, constantan, carbon and others. The unit of electrical resistivity is derived from the equation (1) above after determining ρ:

$\rho=\frac{R\cdot S}{l},\tag{2}$

therefore

$\left[\rho\right]=\frac{\Omega\cdot \mathrm{m}^2}{\mathrm{m}}=\Omega\cdot \mathrm{m}.$

Wires made from a material with a large resistivity are called resistance wires. Their resistivity varies from about 0.42·10-6 Ω·m (nickeline) to e.g 1.4·10-6 Ω·m (Kanthal).

Note: Equation (1) applies accurately to the wire with cylindrical shape, in which the current flows in the direction of its axis, but this is usually met with a normal wire.