Physics investigation
Introduction
In this investigation we are going to investigate the factors affecting the resistance of nichrome wire in an electric circuit
Background Knowledge
The first requirement for conduction is a supply of charge carriers that can move freely through the material. In most solid conductors, notably metals, these carriers are thought to be loosely held electrons. For example, copper has one electron for every atom. The free electrons in a solid conductor are in a state of rapid motion, moving within the crystal lattice at speeds calculated to be around 1/1000 of the speed of light. This motion is normally haphazard (like that of gas molecules) and as many electrons with a given speed move in one direction with the same as in the opposite direction with the same speed. There is therefore no net flow of charge and so no current.
If a battery is connected across the ends of the conductor, an electric field is created in the conductor, which causes the electrons to accelerate and gain kinetic energy. Collisions occur between the accelerating electrons and atoms (really positive ions) of the conductor that are vibrating about their mean position in the crystal lattice but are not free to undergo translational motion. As a result the electrons lose kinetic energy and slow down whilst the ions gain vibrational energy
Electrons move round and round the nucleus in paths called orbits. This is much like that of the way the planets in our solar system revolve around the Sun. the electrons in orbit close to the nucleus have less energy than electrons near the outer core.
Extra Background Information
The total resistance of resistors in series is the sum of the resistance of each one. Each cm of wire has a particular resistance, if you double the length of wire; it is like having two of the shorter wires in series.
