# The Thickness of Nichrome Wire And Its Effect on Its Resistance

Introduction A current is the flow of negative electrons around a circuit. Electrons get pushed out of the negative pole of the cell and drift slowly round the circuit, from atom to atom in the wire, to the positive pole of the cell. A current flowing in one direction like this is called direct current. (d.c.) A cell pushes these electrons around a circuit. It acts as an electric pump. Different cells provide electrons with different amounts of energy, or have greater ?voltage.? When a cell is connected to lamps, the voltage pushes the electrons around the circuit. The energy to do this comes from the chemical energy stored inside the cell. Batteries are a store of chemical energy and the wires are able convert this into electrical energy to be carried around the circuit. The energy that the electrons carry is converted into light energy by the bulbs. After the electrons have provided the bulb with the energy to light up, they carry on their journey around the circuit, but with less energy. Voltmeters measure the amount of energy that electrons have.
Nichrome Wire Everything within a circuit has a level of resistance, measured in ?ohms.? Resistance is a force which opposes the flow of an electrical current around a circuit so that more energy is required to push the charged particles around the circuit. The nichrome wire contains free moving electrons, which resist the flow of the negative electrons supplied by the cell. Therefore, for the electrons to flow through the wire, the voltage must increase. The amount of energy contained by the electrons must be greater than that of the free moving electrons in the nichrome wire, so that they can flow freely. As the voltage increases, so does the resistance. As the length of the nichrome wire increases, there is more space for the free moving electrons to move around inside the nichrome wire. This means that as the electrons try to pass through the wire, they will be resisted by more free moving electrons, causing the resistance to increase. This again increases the force needed to get passed the free moving electrons, raising the voltage. [image] Path of Electrons Free Moving Electrons Path of Electrons This diagram shows the charged particles in competition with the free moving electrons contained within the nichrome wire. It shows how the electrons have to find a route through the free moving electrons which are constantly vibrating and moving slowly around. To find their way through the sea of free moving electrons, they must move around, which uses energy which is why the voltage increases as the resistance increases. Prediction I predict that as the length increases, the resistance will increase in proportion to it. Proportional means that as the length doubles, so too will the resistance. We already know that as the voltage increases as the resistance increases, to provide the electrons with enough energy to bypass the obstacle in their way. This obstacle is the free moving electrons within the nichrome wire, which oppose the electrons as they try to flow freely. As the electrons from the cell move through the wire, they collide with the free moving electrons. Resistance is where the electrons flow towards the positive ions and crash into other atoms that lie in their path. As these atoms collide, kinetic energy is transferred between the atoms. As this energy is transferred from atom to atom, they start to accelerate. However, atoms will always knock into each other, meaning energy will be continually transferred. Atoms move, collide and then transfer energy, creating a circular-like pattern. This transfer of energy is what causes resistance. [image] Therefore, if we double the length of the wire, the amount of free moving electrons within the wire is also doubled. The more electrons there are, the more collision there will be, meaning more energy is transferred and the resistance will double. Energy is never lost or made; it is always converted into a new type of energy or wasted. Apparatus Crocodile Clips 50cm Nichrome Wire 2 Cells Voltmeter Ammeter Insulated Wires Ruler Safety There are many safety precautions I should consider before I start this experiment.
I should definitely not carry this experiment out near water. If
the water comes into contact with the metal as someone is touching
the nichrome wire to change the length, it could cause an electric
shock.
Do not leave the circuit switched on when we are not using it, as
it could heat up the wire, making it very hot to deal with when
wanting to change the length.