How can I investigate the resistance of wire and how it changes with the length of the wireCheers
get a multimeter. get long lengths of different gauge (diameter) copper lead wire. for each diameter, measure the resistance. cut 1ft off, measure the resistance, cut 1ft off, measure the resistance, cut 1ft off, etc etc. plot the resistance vs length for each gauge separately. show that the resistance is linear in the wire length in each case. now use the different diameter data to measure the resisitivity of copper. resisitivity rho = R*A/L R = resistance L = length A = cross-sectional area cheers
If you don't have a multimeter, you can probably see the effect of resistance with a flashlight bulb and a small battery (AA or AAA, etc). Get a spool of wire, needs to be coated/insulated wire. Connect the bulb to the battery with the shortest wire possible. See how bright the bulb is. Then, connect again using the entire spool of wire (hopefully you can get at both ends of the wire while it is still on the spool). The bulb will be dimmer because the voltage at the bulb will be reduced by the resistance of the wire (resistivity per unit length X the length of wire). If the length of wire on the spool is too long, the bulb will not light up at all.
