Investigation of resistivity of nichrome wire Essay Example for Free

Investigation of resistivity of nichrome wire Essay 32 Gauge 28 Gauge Voltage Recorded Percentage Uncertainty % Ammeter The ammeter recorded the current of the circuit with the wire connected to it. 32 Gauge 28 Gauge Current Recorded Percentage Uncertainty %( Current Recorded Percentage Uncertainty. Resistance Thus, as the resistance is calculated using the voltage and current obtained, we have the following resistance percentage uncertainties. 32 Gauge Resistance Uncertainty %( Gauge Resistance Uncertainty % Resistivity This is calculated using the resistance, area and the length. The uncertainties of the resistance and length are used to calculate the uncertainty of the resistivity. The area was not used as it was found by using the gauge value and checked against a referenced site, where diameters were published. As this value was given, the uncertainty was not counted as the method of measurement was not stated. 32 Gauge 28 Gauge Resistivity Uncertainty %(Discussion As the investigation took place, the voltage was increased slowly. This increased the current passing through the circuit. From these values obtained for each of the wires, the resistance and resistivity were calculated. The resistance was calculated from both the values obtained from the experiments and also from the gradient of the graph drawn. This was done so that separate set of resistivities can be obtained and evaluated. As seen from the calculations of the resistance, it is proportional to the length of the wire. The longer the nichrome wire is, the larger the resistance will be. This was certainly the case here as the resistance for the 1 metre wire was more than double that of the 0. 5 metre wire. This larger resistance would be due to the cross-sectional area of the wires. Were the 1 metre wire had a cross-sectional area of 5. 9 x 10-8 m2, the 0. 5 metre was 1. 1 x 10-7 m2, therefore the first nichrome being longer and thinner, causes the resistance to be much larger. The resistivity was calculated for each of the nichrome wires and was found to be very close to one another. The slight difference could be due to experimental errors. The 32gauge wire had a much larger resistance, while being the longer wire and had the thinner cross-sectional area. Taking this all into consideration, the resistivity was calculated at varying voltages and the mean value was 1. 0149 x 10-6 ? m. The gradient from the graph is the resistance, this again was used to calculate a separate value of the resistivity, which was 1. 01496 x 10-6 ? m. This was done as the trend line of the graph was set to the intercept of zero, as when there is no power through the circuit there would be no voltage or current. This value is the same as the value found from the obtained tabulated results. The calculated resistivities for the 28gauge gave similar values. Here the mean value from the obtained current and voltage was 1. 095 x 10-6 ? m, where as the resistivity calculated from the gradient of the graph was 1. 12 x 10-6 ? m. Although these values looking different they are of the standard form of negative 6, meaning they are very small numbers, and therefore this slight difference is minute. Again this resistivity for the 28 gauge in comparison to the resistivity for the 32 gauge is the same, where very small decimal places are slightly out. This investigation led to determining a good value for the resistivity by using two wires of different dimensions. The accepted value for the resistivity of nichrome is 1. 50 i 10-6 ? m. This in ratio to the values obtained is as follows: 32 Gauge 1 This shows that the values obtained are very close to that of the accepted value. To improve the accuracy of the results the experiment should be repeated. In doing so, some variables should be kept constant i. e. the length, gauge or temperature so that an average can be obtained. Bibliography http://www. 8886. co. uk/ref/standard_wire_gauge. htm http://hyperphysics. phy-astr. gsu. edu/hbase/electric/resis. html http://en. wikipedia. org/wiki/Electrical_resistivity Physics Assignment 3 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.