Four factors affecting the resistance in a circuit:
1. Length of Wire
The longer the wire, the higher the resistance. The reason for this happening is because there will be greater amount of atoms in a lengthy piece of wire than a shorter one. This will mean that the collisions between the electrons and atoms will be more frequent as the possibility are high, very likely to happen. The consequence is the current will decrease and the resistance will increase.
2. Width of Wire
If a wire has a long width that will mean atoms will have more space to move freely without any trouble. So this will mean that atoms wont be close to each other, like how it is in a wire that has less greater width and space. The quality of movement of the atoms is much better in a wire that has a long width. All this means, is that a wire that has a good width will allow atoms to flow through a circuit with effortlessness and this will lead to an increase in the current whereas the decrease in the resistance.
3. Material of Wire
A current flowing through a circuit smoothly will be down to how the material of the wire is. If the material of the wire is not good at conducting electricity then the resistance will be greater compared to a wire which the material is good at conducting electricity.
4. Temperature
Temperature affects the resistance in a circuit because if a wire is hot, the atoms will vibrate uncontrollably and collisions will take place because energy levels are high in the circuit because of the hot energy of the temperature. This makes it more difficult for the current to flow which will mean the resistance will increase.
Equipment
- 2 batteries 1.5 volts = 3 volts
- 2 copper wires on ruler 1) 22 SWG 2) 32 SWG
- 2 Crocodile clips
- Resistor (100 cm ruler-Nichrome wire 24 SWG and 32 SWG)
Method: what I did.
Firstly I gathered all the equipments I required to do the experiment. I got all the equipments like the wires etc. I used all the equipment from my equipment list above. I put the circuit together in a series/parallel circuit in which current will flow through the copper wire. I used two different wires which both have 2 different thicknesses. This meant that I could make comparisons between how the thickness affected the resistance. Then I set the power pack to either 3V / 3.5V. Afterwards I made observations on how length affects the resistance by recording my data down for different lengths. I took down the resistance for the wire at 10 cm and 20cm and added on the length with a never changing variety. After doing the experiment for the first time and recording my results, I switched of the power supply so that the wire cools down and don’t overheat. Finally I repeated the experiment twice again because by doing this I can get reliable, useful results rather than just doing it once.
DIAGRAM Of The Circuit
This diagram below shows how my circuit will be set up. It shows the different components and where it will be placed in the circuit.
KEY
= AMMETER
= VOLTMETER
= POWER PACK
= RULER
Safety
Safety is a very important matter. To make show everyone is safe I have to use the correct amount of voltage. If the voltage is too high, the wires will overheat and burn. That will mean the risk of a fire will be high, if I use voltage exceeding the limit I supposedly have to use. In addition to this when I’m doing the experiment I have to handle the wires with care as they are likely to be hot or I may burn myself if I don’t. Also I have to be careful with sharp objects, like the crocodile clips. I have to clip the crocodile clip on the wire carefully or I may cut my fingers by the sharp end of the mouth of the clip.
Keeping The Experiment Fair
Keeping the experiment fair is very crucial in me getting accurate reliable results. The only thing I have to do to keep the experiment fair is only change the length of wire which is the variable. The only other thing I have to do and be aware of is, keeping things that can change my results. For example I have to use the same amount of volts being used in all the times I repeated the experiment. Also the temperature of the wire should also be roughly the same. Other things is to keep the measuring device, crocodile clips on tightly and the circuit should in the same place. If the circuit is moved the flow of the electricity may differ from other experiments.
Results
These charts below show my results I got working with my group for the different thicknesses of wires.
24 SWG Wire
This chart above, shows us a chart for the 24 SWG (thickness) wire, showing the results I got after carrying out the experiment. I have done the experiment over and over again 3 times so I could get reliable, accurate results. I found out the average by adding all the attempts I did to make the experiment fair and then divided it by three (the number of times I redone the experiment). This is what the chart shows, the average voltage (volts) and the average current (amps)
32 SWG Wire
This chart above, shows us a chart for the 32 SWG (thickness) wire, revealing the results I got after following and finishing my experiment. I repeated the experiment three times. I have done this because so I could get reliable, accurate results. I found out the average by adding all the attempts I did to make the experiment fair and then divided it by three (the number of times I redone the experiment). This is what the chart shows, the average voltage (volts) and the average current (amps)
The Following Charts Show The Averages Of The Wires
24 SWG Wire
This table above the average results of the 24 SWG Wire. You may witness that on the results table on the column of the Length of Wire is blank. This was due to the reading going of the scale on the measuring equipment. It did not have enough scale to go low enough for the volts and high enough for the current. So my group couldn’t record this. It was inaccurate. To find out the resistance I used the formula R = V ÷ I.
32 SWG Wire
This table above shows the average results of the 32 SWG Wire for all three attempts. The resistance was calculated by using the formula R = V ÷ I.
The following graphs below are the graphs for the 24 SWG Wire. It shows us the following three things. Firstly if the average of the voltage is affected by the length of the wire. Secondly if the average current is affected by the length of wire. Finally if the resistance is affected by the length of the wire.
Graph 1
This graph shows us the average voltage and the length of the wire. From analysing the graph I notice that there is a positive correlation between the voltage and the length of the wire. It shows and suggests that if you increase the length of the wire the voltage increases too.
Graph 2
Graph 2 shows us the average current and the length of the wire. From observing my graph I noticed that there is a negative correlation. We can see at first the current is high but than it steadily goes down at a constant speed. As the length gets longer the current lowers. The reason for the current going down as the length increases, is because as the length of the wire increases so will the number of atoms for the electrons. get through the wire. It is hard for less electrons to pass through the wire which means the current decreases.
.
Graph 3
The final graph, graph 3 shows the resistance and the length of the wire. From the graph I can see that there is a strong positive correlation. It shows and tells us that as the length of the wire increases, so does the resistance. We can see from the graph, from the length of the wire at 10cm to 100cm, the resistance increase steadily. This suggests that the increase of the length of the wire should be proportional to the resistance increase.
Correlation between Resistance and Current in the 24 SWG wire.
The graph below shows the correlation between the average current and the resistance. From analysing the graph I have found out that the current decreases when the resistance increases. At first we can see from the graph that the resistance is high when the current is low. But as the current increases the resistance decreases. This is due to as there are fewer electrons to get through the wire, the current decreases as it can not flow through the wire freely and this leads to an increase of the resistance.
Correlation between Resistance and Voltage in the 24 SWG wire.
The graph below shows the average voltage and the resistance of the 24 SWG Wire. It shows that as the resistance increases the voltage increases too.
Average Graphs OF The 24 SWG and 32 SWG wires
24 SWG Wire
The graph below shows the average resistance of the 24 SWG Wire. The average resistance has been designed on a scatter diagram as you can see below. We can clearly see a strong positive correlation in this graph between the length and the resistance. It shows us that as the length of the wire increases, so does the average resistance. This tells me my prediction was correct “as I increase the length of the wire, resistance will also increase.” This was also done particularly to check how reliable my other previous results were and from this evidence, how the graph is they are truthful.
Correlation between Resistance and Current in the 24SWG wire.
The scatter diagram below shows the correlation between the average current and the resistance. The diagram shows that as the current decreases as the resistance increases.
This is because when fewer electrons get through the wire the current decreases as it can not flow through the wire easily therefore leads to an increase in the resistance.
32 SWG Wire
The scatter diagram below shows the average resistance of the 32 SWG Wire. From observing the graph we can undoubtedly see a negative correlation between the length and the resistance. Similarly to my other graphs it shows us that, the increase of length of the wire leads to decrease for average resistance.
Evaluation
My experiment I did, was only half reliable because overall my results as a whole were not very truthful and realistic. I could improve my method and how I did the experiment for next time by thoroughly checking the four factors that effect resistance. This is because only wire of my wires prove my predictions correct and that is the 24 SWG Wire