Resistance investigation Essay Example for Free

Resistance investigation Essay Resistance is the opposition to current and voltage within a given material. George Ohm discovered the concept of resistance in 1826. He stated that the current flowing through a wire is proportional to the potential difference across it as long as the temperature remains constant. The formula to calculate resistance is Resistance (measured in Ohms)= potential difference across a wire (volts) Current through a wire (amps) In this investigation we are going to find out how resistance changes in relationship to when the length of a wire is changed. We will take readings every 10 cm because this should give a substantial variation in the readings and go up to 100 cm because this will give us a sensible set of results to work with. To ensure that the experiment is safe we will have to clear the work area and make sure that it is clean and dry, and keep the current low, in this case two volts. I predict that as the length of the wire increases the resistance will also increase in direct proportion, as there will be more particle collisions in the longer wire. In addition the free electrons in the outer shell have to carry the charge further, which also increases the chances of collision. To make the experiment a fair test we will use 2 volts throughout and include a switch in the circuit, which will enable us to control that the circuit is only on when we are taking readings. It will therefore obey ohms law, as the temperature will remain cool, and the cross sectional area of the wire will also remain the same. We will keep the same apparatus throughout the experiment and will take more than five sets of results to ensure that we have a good statistical average. The only thing that we will change is the length of the wire. The apparatus we will need in the experiment are a power supply, wires, a switch, a 1metre ruler, a voltmeter and an ammeter. Results These are the sets of results that I obtained: Distance (cm) Voltage (v) Current (a) Resistance (ohms). From these results we have found out that as the length of a wire increases so does the voltage and resistance, whereas the current reduces. The data shows that the distance of a wire does have an effect on the resistance through it. This is because as the length of the wire increases the likelihood of collisions between the nucleus of the atom and the electron which carries the charge increases. On the graph the line of best fit shows that that there is a good correlation of the data showing that there is a direct and proportional relationship between the length of a wire and the resistance. This proves that my original prediction correct that the resistance of a wire will increase as the length does. Evaluation The method used for the experiment worked well and we were able to gain the results needed to make a conclusion. The accuracy of the data was on the whole good but there were two odd results. These were anomalies as the resistance was lower on average than the resistance from the reading taken from a 10 cm shorter wire. The method for the investigation was well suited to the experiment. To improve the reliability of the results we could keep the room temperature constant, and be more accurate in measuring the length of the wire. We could also use more accurate voltmeters and ammeters. Due the close position of the points plotted on the graph there is enough accurate information obtained from the results to support the definite conclusion that as the length of the wire increases so does the resistance. To improve the results we could repeat the experiment but take readings at different or more frequent intervals . We could also take more sets of results.