The length of an electrically conductive metal wire Essay Example for Free

The length of an electrically conductive metal wire Essay The results of the experiment, however, do not adhere to the direct proportionality relationship predicted in the hypothesis. In the hypothesis a zero value for wire length is predicted to induce a zero value for wire resistance. Intuitively, this should be the case. However, regardless of what linear line of regression one examines from the ones plotted, it is obvious that the experiment indicates the existence of electric resistance even when the wire has no length. This result is indicated through the intersection of the regression curves with positive Y values. The zero length resistance varies from 0. 02 to 0. 0578 ohms. The existence of errors in the experiment, namely systematic ones, may help explain the result. Errors The method for the experiment contained some errors. Some of those are evident when examining the results of the experiment. Others are very small, and did not have a great effect on the final outcomes. The most prominent source of error had to do with the existence of additional resistance in the circuit used. The metal wire used, since it wasnt a wire meant for electrical circuits, naturally offered the greatest resistance to current flow. Nevertheless, the connecting wires also contained some inevitable resistance. Additionally, the ammeter, and power supply also had some internal resistance (the voltmeter did as well, but this is necessary for the procurement of accurate voltage values). Since current flowed through all those, the resistance values obtained did not represent solely the resistance of the metal wire. This probably explains the systematic error foreboded in the conclusion. The existence of resistance in other pieces of apparatus except the metal wire allowed for the possibility of resistance even when the metal wire would have no length. Another source of error existed in the measurement of the wire length used in the circuit. The metal wire used was manipulated to assume a straight form. However, even after it was firmly attached to a table, it was not fully stretched. In some of the cases, it may have bent slightly, making the total wire length greater than what was measured. This could have contributed some additional, and unwanted, resistance to the wire. After all, a longer wire offers more resistance to current flow. Altogether, an addition to the systematic overestimation of the resistance of the metal wire also came from this error source. Though negligible, some error could have sprung from the heating of the wire used. As current was allowed to flow through the metal wire, atoms of the wire collided with the electrons flowing, causing the wire to heat up. If the wire werent allowed to cool down before another measurement was taken, then it would have posed additional resistance to the subsequent current flows, since resistance rises with temperature. Again, the method used in this experiment allowed for the existence of additional resistance in the wire that was not taken into account. Improvements In light of the errors noted, or for the need to perfect other experiments of the same type, improvements to the method can be offered. Firstly, the error involving the length of the metal wire could be minimized in two ways. Either a much more flexible wire could be used for the allowance of a straighter metal wire, or a greater effort could be made to stretch the existent wire so that it is much more straight. In both ways, the length measured for the metal wire would be more representative of the actual length being used. Another improvement could deal with minimizing the existence of additional resistance in the circuit besides that of the metal wire examined. This could be done in several ways. The connecting wires used could be shorter, meaning their resistance would be smaller. A power supply and ammeter with smaller internal resistances could also be used. In either of the cases, additional resistance in the circuit would decrease, and the systematic error in resistance minimized. Finally, though not too necessary, it is possible to improve the experiment by minimizing resistance distortions due to temperature increases. A simple way would be to wait at least 3 minutes between each current flow induced through the wire. This way, the whole circuit together with the wire itself would have time to cool down. Wire temperature would hence not be a factor distorting the resistance values being measured, as it would be more or less the same in all measurements. Nevertheless, it may be that the distortions to resistance values caused by temperature increase are so small that this improvement on the whole is futile. Another minor improvement to the method would be the use of a switch. This way, current flow could be initiated and stopped on demand (i. e. immediately). It would be of course necessary to use a switch that offers little resistance. Otherwise, the current construction of the circuit is preferable.