# Resitances of a wire:it is about how length effects the resistance of a wire.

Essay by trizeHigh School, 10th gradeA, December 2003

Resistance in a wire

Planning -

The resistance of a wire can be affected by certain factors:

Length of wire

Cross sectional area

resistivity (type of metal)

Type of wire

Temperature

I chose to investigate how length affects the resistance in a wire. This means that the other factors (variables) must be controlled. This means I must keep the same type of wire, the same material of wire (a preliminary experiment will help determine this), and the same cross sectional area and maintain a constant temperature of the wire as any increase in temperature increases resistance. These factors must me kept controlled to ensure a fair test.

Preliminary Experiment

I conducted a preliminary experiment to determine the best wire to use for my experiment. I tested two wires that are frequently used in electronic circuits, copper and in-home. We tested an equal length of each wire to determine a range of voltages that could be used for the experiment before the wire got hot (a rise in temperature would increase resistance).

Copper started to warm up at around 0.50 volts and nichrome at about 2.00 volts. I will use nichrome in my experiment as it does not warm up as quickly and a wider range of results can be obtained, making the experiment more fair and precise. If more results are taken I will be able to plot a better graph with clear shape and form.

Scientific theory

Electric current is the movement of electrons through a conductor. In this experiment a metal wire will be the conductor. When resistance is high, conductivity is low. Metals conduct electricity well because the atoms in them do not hold on to their electrons very well. Free electrons are created, which carry a negative charge, to 'jumpÃÂ´ along the lines of atoms in...