Internal Resistance Investigation :: Papers

Internal Resistance Investigation I will conduct the following investigation with the aim to find the internal resistance of a lemon battery, which I will construct myself. The variables that could affect my experiment are as follows:  · Size of lemon - I will conduct my experiment in no longer than an hour, allowing me to use the same lemon for all results  · Size of metal electrodes - I will use the exact same electrodes throughout the whole experiment  · Length of any connecting wires - I will use the exact same wires throughout my experiment and will not break the circuit once I have started collecting data  · Resistance in the circuit - I will vary this using a highly sensitive variable resistor as shown in my method. To make my experiment fair I will only vary the most relevant variable to what I am investigating, which is the resistance in the circuit. All the other variables will be kept the same throughout the experiment as stated above. In my experiment I will need to measure the terminal pd, V, and the Current, I (in amps), for many values of resistance, R (in W), I will measure these as I know that V=E-Ir so these are the values that I need to know if I am to eventually calculate the batteries internal resistance. I think that to make my graphs and conclusions accurate I will need to take at least 10 measurements, covering the full range of the variable resistor I have available to me. To improve the accuracy of my experiment I will take my readings to the most decimal places as my voltmeter and ammeter will allow me. To do this I will need to make sure that I am using the milliamp/volt or 2 amp/volt setting on my meters. As I said before I will also do all I can to ensure that no other variables other that the one I am investigating are varied at any time during the experiment. It is hard to determine the exact resistance that a variable resistor is set at