An investigation into the factors affecting the resistance of a wire Outline: Start with a simple paragraph saying what you are going to do. Factors affecting resistance of a wire: Material, Temperature, Length and Cross-sectional area Material is the same (constantan) and we are trying to keep the temperature constant. (you need to say this) Length and cross sectional areas will be varied. This needs to be done in two separate experiments (Fair Test) Length and cross-sectional area are the independent (input) variables.
The dependent variable (output) is the resistance Science (essential). Use a textbook/internet/secondary source to find this information. Say where you found it, it must be relevant to GCSE! Detailed knowledge will get the higher marks. Ohm’s Law which gives the relationship between the resistance, voltage and current. Give units and equations (show correctly) How resistance is related to length (draw a picture, it can also be used as your prediction). Back it up with an explanation (longer path for electrons)
How resistance is related to cross-section (draw a picture, it can also be used as your prediction). Note, there are two plots here! Back up with explanation (more pathways). Prediction: Say what you are doing and use your science to back it up Safety: The experiment should be safe and you will follow safe laboratory practice Equipment: At a glance you might well need: crocodile clips, power supply, voltmeter, ammeter, variable resistor, leads, constantan wire, meter rule, micrometer (to measure wire thickness).
Include a circuit diagram. Remember you might need to change equipment after the preliminary experiment. Say what any equipment is used for. Preliminary Experiment: The purpose is to see if your method is suitable to test your prediction, make sure things work and make any changes. You will need to record these results and plot things. Use this information carefully and mention if you make no changes or changes. If the preliminary data looks sensible, then you are on the right track. Repeating Measurements:
The same idea as for Chemistry, there needs to be enough different lengths (5 min) and cross-sections (5 min). Measurements need repeating and checking. If a particular set of data is not looking good, discard it and take another measurement. You ideally want 3 sets of similar data! Precision: Voltages, currents, resistances, lengths and wire thickness need to be recorded and presented to the correct level of precision. Say what ranges data will be collected over etc. Data Tables and Plots:
Must have clear and correct units, titles, etc. These can be presented using spreadsheets. Plots must be done on graph paper (not computer). Must cover more than half of sheet and have suitable axes. Graphs must be correctly labelled and the points should be crosses drawn in pencil. Best fit-lines should also be shown. Seek help on this if not sure.
References: Most likely you found out things, say where you found this information. Fair Test: Absolutely crucial to show. In a fair test you only allow one thing to vary.