From theses sources I found:
- ‘Resistance is a force which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long, e.g. the filament across an electric bulb is quite thin as needs to resist the flow of particles for the bulb to glow’
- ‘If a solution is made more concentrated, it means that there are more particles of a reactant knocking about between the water molecules, which make collisions between the important particles more likely’.
Hypothesis/Prediction:
I predict that as the length of the wire increases so will the resistance. This is due to the fact that in a longer piece of wire there would be more atoms for the electrons to collide with, therefore the resistance would be greater. I also think that the rate at with the resistance of the wire increases will have a connection with the length.
Apparatus:
- 100cm long wire
- Resister
- Power pack
- Wires
- Crocodile clips
- Voltmeter
- Ammeter
- Bulb
The experiment will be done using the apparatus shown above, and ready-made instructions of which I have to abide by.
Key factors/variables:
In the experiment I shall only change one factor, this will be the length of the wire. This has been chosen because it will give good results, as I will be able to compare results from shortest wire to the longest. This should also affect the resistance of a wire in the ways I have stated in my prediction.
Fair test:
Everything in the test will have to be kept the same due to the fact that if anything is changed whilst the experiment is taking place the experiment will be unfair. The experiment will be closely monitored to do this.
Method:
Set up the apparatus to the specific needs.
A length of wire has been attached to both ends of a metre ruler; this is attached to the circuit with crocodile clips.
The crocodile clips will be moved to different lengths, from 10cm to 100cm, goin up in 10cm each time. I will take the readings of all these using both the voltmeter and the ammeter until I have a full set. Then using the formula R=V/I I will work out the resistances
Safety:
Throughout the experiment, safety should always be taken into account. Making sure all the wires are connected and that there are no short circuits. I will also make sure that no water comes into contact with the circuit as all of these will result in an unfair test.
Results:
Graph:
Conclusion:
We can conclude that these results are accurate as they show a general trend, and they are very close to the line of best fit. The results, which have been obtained from the experiment, clearly show that as the length of a wire increases so does the resistance. This is also shown in my prediction and hypothesis, which explains why the experiment went so well.
Form my results I can state that my prediction was right. The resistance changed in proportion to the length. This is because as the length of the wire increased, the electrons that made up the current had to travel through more of the fixed particles, causing more collisions and therefore a higher resistance.
Evaluation:
I believe that the experiment went well. I collected sufficient data in order for the experiment to be carried out fairly and precisely. Everything was successful and my final results were proved to be accurate and collaborated with my predictions.
The results that have been obtained from the experiment are accurate. We can see this as the graph shows a general trend, and that they are very close to the line of best fit. I only had time to do the experiment once; therefore doing the experiment 3 times would collect more precise and accurate results. Apart from that I don’t think could have made it more accurate; I feel that my results prove the significance of the experiment.
