the ions in the wire.
●As the length of the wire increases, the number of free electrons
also increase. This mean there will be more collisions of free
electrons. The result; more energy being lost.
●By doubling the length of the wire, it doubles the number of
resisting ions, therefore it takes twice as long for the charge to
pass through it.
Diagram
Preliminary Work
I have done preliminary work to check if the way the apparatus and the way I the experiment was carried out worked. It also allows me to make changes to the actual experiment if i find any queries, thus making it a better and more accurate investigation. I will also make my results more reliable because i can compare them to my actual results.
Diagram
Method
● I will collect all the equipment required and set it up like
the circuit diagram above.
● Then I will collect a meter ruler to measure lengths of
wire easily and accurately.
● I will then record results at 20cm, 40cm, 60cm, 80cm and
100cm into a table.
Fair Test
To ensure that the investigation is carried out fairly and the results accurate and reliable enough to be used, a number of things must be followed. The only variable in the test isthe length of the wire. The wire must be pulled tight against the ruler to make sure it is an accurate as can be and then taped in place at the end. The same circuit and battery must be used throughout the experiment. Changing equipment can give different results as some equipment is old and some are new.
Preliminary Results
Conclusion
I will be able to compare these results with my actual results and this will help me see if they are accurate or not.
Actual Work
Diagram
Equipment
Equipment Needed:
●Voltmeter
●Ammeter
●Wires
●Crocodile Clips
●Meter Ruler
Method
●I collected all the equipment I needed and set it up as in the diagram. (See Preliminary Work)
●Then I measured 10cm on the ruler and took a recording for Voltage and Current. I worked out resistance using voltage and
current that i had jus recorded. (Voltage/Current = Resistance)
●I then repeated this for measurements 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm and 100cm and wrote down the
results as follows.
Results
V = Voltage.
I = Current.
Ω = Resistance.
Analysis
My graph results show that as the length of the wire increases so does the resistance. I know this because the line I have drawn is directly proportional. I think my results are correct because:
- Doubling the length of the wire doubles the number of resisting ions therefore it takes twice as long for the charge to pass through it.
- As the length of the wire increases then so does the number of free electrons. This mean there will be more collisions of free electrons.
My graph results support my prediction.
Evaluation
I think that my results are accurate and reliable because they have enabled me to draw a line of best-fit graph. The graph shows a pattern between 10cm and 100cm and I was able to make a simple conclusion.
My results are quite reliable because I made 3 measurements of current and voltage for each length and used the average values to calculate Resistance. Even with that I still had two anomalous results at lengths 70cm and 80cm.
The experiment I did was successful but I did have some difficulties doing it. If I could redo the experiment I would:
- Make sure that the wire is always taut. If the wire isn’t taut the lengths I measure could be inaccurate and my results wouldn’t be reliable.
- I would make sure that when I used crocodile clips they didn’t scrape the wire because this may affect the thickness of the wire and it would make my results unreliable.
- Make sure that the batteries I use are not old or different as they may have different voltages from each other. This would again make my results unreliable and inaccurate.
