Investigation of the Variation of the Resistance of a Wire with Length I intend to investigate the effect of length on the resistance of a wire. Introduction There are various factors which effect the resistance of wire, These are: 1. The diameter of the wire ? the smaller the diameter a wire has the smaller the cross-sectional area is. It is known that the resistance is inversely related to cross-sectional area i.e. as the cross-sectional area increases the resistance decreases and vice versa. 2. The length of the wire ? the longer a wire is the greater the resistance is i.e. the resistance is proportional to the length of wire. 3. The resistance of the wire is related to the material the wire is made from. The property of the material that effects resistance is known as resistivity. To quote from The Hutchinson Dictionary of Science " Resistivity in physics, is a measure of the material to resist the flow of an electric current. It is numerically equal to the resistance of a sample of unit length and unit cross-sectional area, and its unit is the ohm metre." 4. The resistance of a wire also varies with temperature, most materials show an increase in resistance as temperature increases. Of the four factors the easiest in practice to investigate is the variation of resistance with length