The Science
In every circuit there is always resistance. Resistance tells us how easy it is for electrons to move around a circuit. The greater the resistance in a circuit the harder it is for electrons to flow around a circuit. Resistance is measured in Ohms (Ω). The reason there is resistance is because of protons. As electrons flow around a circuit protons get in their way, making it harder for the electrons to travel round the circuit. So if there is a long piece of wire and a short piece of wire, both of which have an electric flow in them, the long piece of wire will have a larger resistance because there are more chances, in a longer piece of wire, for the protons to get in the electrons way, which slows them down. In the short wire there are less chances for the protons to get in the electrons way, which creates resistance. To show this here are two diagrams
In this long piece of wire the protons have more chances to get in the electrons way, which increases the wires resistance; this makes it harder for the electrons to flow.
In this short piece of wire there are fewer chances for the electrons to get in the protons way, which makes for less resistance in the wire.
There are also three other factors that can affect a wires resistance. These are a wires width, what it’s made of and how hot it is. If a wire is thicker then there is more space for the electrons to flow and less chances for the protons to get in their way. To show you what I mean, here is a diagram.
In the thick wire the electrons have more space to travel in the wire. This makes the protons have less chance of obstruction the electrons and making the resistance of the wire increase.
As you can see, in this thinner wire, the protons and electrons are closer together making them collide more and increase the resistance of the wire. What a wire is made of will affect its resistance. Since plastic is an insulator it’s resistance is very high. This would not make a good wire because of its high resistance. Copper is a conductor and will let electricity flow through it very easily; this is because it has a low resistance. Also the temperature of a wire makes a difference to how high or low a wires resistance is. If the wire is hot its resistance increases. If a wires temperature decreases then its resistance will as well.
Results
To present my finding I have decided to show them in two forms. One is a results table (as shown below)
Also I am displaying my results in the form of a graph
What I Found Out
After I looked at my results I found out that my hypothesis was right. The length of a wire does affect the wires resistance. The longer the wire an electrical flow is going through the higher the wires resistance. If the wire is a short wire then it’s resistance is lower. I also found out some more interesting facts while looking over my results. I found out that resistance is not affected by either voltage or current I also found out that if the resistance is high then the current will be low and if the resistance is low the current will be high. This means that the current is inversely proportional to the resistance. The voltage of the circuit also affects the current as well. If there was a high voltage but a low resistance then the current will be high because it is inversely proportional to the resistance and proportional to the voltage. Also I have used the formula R=V÷I and have proved that it works.
The pattern on the graph is of a positive correlation. This is because the resistance rises with the length of the wire. So as the length goes up so does the resistance.
Evaluation
The results I collected are pretty much all what they should be but the only real problem with them was the third time I measured the voltage for 400mm it is the same as 500mm but the current had changed. I put this down to a human error of recording the results. I have collected enough results to prove my original hypothesis and have an accurate resistance average at the end of the practical. To improve the plan I already have I would make sure we use a lower voltage so as not to overheat the wire at all, making for more accurate results. Also if I used better and more accurate readers for volts and amps then we would have had even more accurate results.
Further work I could do for this investigating would be how the width of a wire affects the resistance. I wrote a few sentences on it earlier but and investigation on it would be more work I could do on this investigation. Also what the wire is made of can affect its resistance so I could plan an investigation on how different metals and materials have a different resistance. Also heating or cooling down a wire can increase and decrease that wires resistance. I have written some information on all these three earlier and can serve as a simple hypothesis for these three new investigations
