Investigate one of the factors effecting current flowing through a wire.

Investigation – Factors effecting current flowing through a wire

Aim - To investigate one of the factors effecting current flowing through a wire.

Factors –

Length – The length of a wire affects the resistance. The longer the wire is, the higher the resistance, and so the current in the wire is lower. This is because in a longer piece of wire there are more particles. It is harder to pass current through many particles than it is just a few.
Diameter – As diameter increases, current increases. To explain this I will use the model of people going through a door. If the door is small, it will take people a long time to get through it. If the doorway is large, it will take the same amount of people a much shorter time to get through. This is the same as electrons moving through a wire.
Temperature – When temperature is high, resistance is high. This means current is low. This is because when the wire heats up, the particles start to vibrate quicker. The vibrating particles restrict the flow of electrons, reducing the current.
Voltage – Ohms Law states that when voltage increases, current will increase proportionally if the temperature is constant. This is because voltage is the push of electrons through a circuit. If the electrons have a bigger push, it is easier for them to travel through the circuit. This is why current increases.
Resistance – Wires with a higher resistance will have a lower current flowing through them. This is because wires made of a resistant material restrict the electron flow through them. Wires with a low resistance are good at letting electrons flow through them.

Prediction –

I have chosen to investigate how length of wire effects current flowing through it. I have chosen this because it is easy to get a wide range of accurate results. Accurate results are achievable when varying the length because we can fix accurately all other factors. It is also practical to investigate length because it is available as a continuous variable, whereas area and resistivity are discrete variables.

I predict that the longer the length of wire, the higher the resistance and so the smaller the current in the wire. This is because a longer piece of wire has more particles, and so it is harder to pass current through many particles than just a few. This can be seen by looking on a small scale at the action of individual electrons (the flow of electrons is the flow of current). Electrons move in a metal to produce a current if there are two conditions;

1. There must be a potential (voltage) difference across the wire.

2. The electrons must be in the conduction band.

Electrons are given energy by the voltage provider (in our case a 2V power pack), which propels them into the conduction band. However, there are still small atoms in the way of the electron, and electrons don’t move from side to side to avoid obstacles. Every time an electron hits an obstacle it slows down and gives off some energy, thus the flow of current is reduced and the wire becomes slightly warmer.

The power ...