Resistivity Coursework Essay Example for Free

Resistivity Coursework Essay Theory suggests that the resistance of a wire is found with this formula: R=? L/A R = Resistance ? = Resistivity of wire L = length of wire A = cross-sectional area I will now perform an investigation to confirm the legitimacy of this formula and confirm a value for ? in a Nichrome wire. Planning A4c: Fully labelled Diagram A4d, A6d: Comprehensive list of Apparatus including Instrument Ranges Variable power supply unit Analogue ammeter, accuracy 0. 01A, range 0 to 1. 0A Analogue Voltmeter, accuracy 0. 1V, range 0 to 5V Copper leads x5 Crocodile clip x2 Nichrome Wire (diameter=4. 57 x 10-4m). Ruler, accuracy 0. 001m, range 0 to 1. 000m A2c: Safety Confirm the Initial power supply is at 0 volts other wise huge voltages will most likely cause unnecessary heating in wires including the Nichrome not only a hazard but may compromise my readings. Make sure my practical investigation is free of all or any obstructions; any unnecessary wires may cause a short circuit leading to damaging the power supply unit, ammeters and voltmeters. A4b, A6a: Identifying Variables and Constants The variables in this investigation are voltage (V), resistance (R) and length of Nichrome wire (L). Resistance and length are directly proportional to each other. Constants are current (I), cross sectional area of wire (A) Resistivity (? ) and temperature of the Nichrome wire. An R against L graph must look like this, (look below,) if resistance and length are directly proportional to each other. A4c: Detailed Plan   confirm power supply unit is at 0v construct apparatus as illustrated in diagram   connect voltmeter negative crocodile clip on 0. 100m   increase current to 0. 30A   take reading from voltmeter as quickly as possible for the wire to remain at the same   switch off power when entering the reading into required data   connect the voltmeter negative crocodile clip to increased 0. 200m   repeat process till I reach 1. 000m   repeat the whole process again but with 0. 60A   plot a graph of R vs. L which is required to be a straight line through the origin   use the graph of R vs. L to find the value of R use Display complete essay. The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section. Download this essay Print Save Heres what a teacher thought of this essay 4 star(s)