Investigating the Resistance of Wires :: Papers

Investigating the Resistance of Wires Aim: To investigate how the diameter of a constantan wire will affect its resistance and hence the current flowing through it. Prediction: I predict that the thicker the diameter the less resistance there will be. Reason: In a metal, some of the electrons are free to move between the ions, to form a "sea" of electrons around the positive metal ions. Metals that are good conductors have more "free" electrons and therefore these electrons move easily around the positive metal ions. However in metals that have fewer "free" electrons, the ions act as obstacles to the flow of electrons and therefore the wire has resistance. The current becomes stronger with the more electrons that flow through a wire in one second. As the diameter increases the electrons will have more available routes between the ions to pass through per second, making the electron flow greater hence the current becoming stronger. See figures 1 and 2: [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] In a larger diameter, there [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE]Figure 1: are more routes for free [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] electrons to travel [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] through. [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] In a smaller diameter, [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE]Figure 2: there are fewer routes [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] for the free electrons [IMAGE] to travel through. Plan: I will set up a circuit consisting of a cell, ammeter, voltmeter and 50cm of constantan wire. The diameters I will use are as follows. 0.56mm, 0.43mm, 0.38mm, 0.32mm, 0.27mm and 0.20mm. I will measure these diameters with a micrometer. I will take three readings of the current and potential difference for each different diameter of the wire and take an average for V (potential difference measured by a voltmeter) and I (current measured by an ammeter) in order to get the most accurate results possible. I will then plot these results in two graphs one plotting V against I and another plotting the average resistance (using ohm's law R=V/I) against the diameter.