# Investigating the Resistance of a Wire

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Investigating the Resistance of a Wire Planning -------- Aim The aim of my investigation is to investigate how length affects the resistance of a wire. Resistance is the force, which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. Resistance is measured in ohms. Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire. Plan of the method to be used:- The resistivity of a wire can be determined using the equation P= RA/L Where: R:- Is the resistance of the wire in ohms and can be determined using the equation R=V/I where V is voltage in volts and I is current in amperes. L:- is the length of the wire used in metres. A: - Is the cross-sectional area of the wire in metres square and can be determined using the equation A= Ï€(d/2 x10 Â³)Â² where d is the diameter of the wire in mm. I will plot a graph of length on the x-axis against resistance on the y-axis. From the relation R = PL /A which corresponds to the straight line equation y=mx+c the graph should be a straight line passing through the origin where m is the gradient of the straight line graph that corresponds to P/A. Since the cross-sectional area of the wire can be found by measuring its diameter. Therefore the resistivity of the wire can be calculated. Apparatus list:- t Battery 1.5V t Switch t Metre Rule t Voltmeter t Ammeter t Wire 100cm (under test) t Crocodile clips t Connecting wires t Micrometer t Sellotape Apparatus Range Sensitivity Metre Rule 0-100 cm 0.1 cm Micrometer 0-25 mm