Ohm’s law Essay

Predictions 1. The longer the wire, the more it will resist the flow of electrons 2. The wider the wire the less resistance it shall have. 3. Copper will be the wire which has the less resistance. 4. The different types of wire will have different levels of resistance. Accuracy I am intending to also get a reading for the length â€Å"zero† also using the crocodile clips and keeping the circuit identical. This shall be my â€Å"control†. I suspect that there will be resistance both in the circuit wires and in the multimeters. This will mean that the values obtained for resistance of the wire shall be slightly too high. By subtracting the resistance value of the circuit wire from the resistance calculations I will get a more accurate set of results. Also as I intend to draw a best fit line for my results, if all the points are slightly too high the gradient will be dramatically altered. The way in which the readings are being taken is designed so that the readings are random but in an orderly way so that I can spot any mistakes. Method Method used The method used was identical to that explained under the planning section, above. The results (i. e. readings on the multimeters), were taken down and put into tables. The results were as follows: Results For nickel chromium wire, SWG 30 Length (cm) Width (mm) Current Readings (Amps) Voltage Readings (Volts) T3Length (cm) Width (mm) Current Readings (Amps) Voltage Readings (Volts) For nickel chromium wire, SWG 22 Length (cm) Width (mm) Current Readings (Amps) Voltage Readings (Volts) For copper wire, swg 30 Length (cm) Width (mm) Current Readings (Amps) Voltage Readings (Volts) Try 1 Try 2 Try 3 Ave. Try 1 Try 2 Try 3 Ave. For constantan wire, swg 30 Length (cm) Width (mm). Current Readings (Amps) Voltage Readings (Volts) For manganane wire, swg 30 Length (cm) Width (mm) Current Readings (Amps) Voltage Readings (Volts) Resistance values For Nickel Chromium Wire, SWG 30 Length (cm) Current (A) Voltage (V) Resistance (? )For Nickel Chromium Wire, SWG 28 Length (cm) Current (A) Voltage (V) Resistance (? ) For Nickel Chromium Wire, SWG 24 Length (cm) Current (A) Voltage (V)Resistance (? ) Patterns and trends It can be quite clearly seen in most of my results that when a graph of length and resistance are plotted the result is a straight line. In my case I have obtained a scatter graph with a very strong positive correlation. In graph 1 It can be seen that there are four straight lines passing through the origin. These straight lines are the values for Nickel Chromium at different gauges. The gauge values are as follows: Gauge Diameter (mm)   graph two, it can seen that this is not a relationship of direct proportionality as the correlation doesn’t â€Å"point† towards the origin. Also from graph one, it can be seen that the resistance increases as the length does. All these lines are straight and they all pass through the origin, so I think it is appropriate to conclude that Resistance is directly proportional to the length of the wire. Finally it can be seen from graph three that the resistance in different types of wire varies according to the type. Keeping the gauge constant this was tested and the results were as follows: Nickel Chromium is the most resistant, Manganane is the second most resistance, Constantan is third, And the least resistant is copper. All the evidence her proves that my results agree with my hypothesis. (c. f. section P). Evaluation Reliability The reliability of these results is quite good. This is because the procedure is relatively straight forward, and the numbers are not difficult to record. I think the results are certainly reliable enough to support both of my conclusions firmly. Anomalus results. There are a few anomalus results throughout the experiment. The resistance values in the table are not always increasing, and this is not always occurring at a steady rate. Good example of which are the readings for 40 and 50 cm on the copper wire. I think that this is just a mistake in taking down the results or possibly we didn’t wait foe the voltmeter to stabilize. Experimental errors These could include many things, the most likely of which are a short circuit, The wire may have heated up causing less resistance, and the readings on the multimeters could have been inaccurate. Further work This could include finding a more varied set of results, testing more types of wires. It could also include taking more readings to get better averages. I would suggest using all the rest of the equipment in the same way. Also one could try to investigate temperature changes by using insulated wires and a tray of cold/warm or hot water. 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.