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# Investigate the resistance of a wire at different stages on the power supply.

Extracts from this document...

Introduction

Planning

This is the part of my coursework where I am going to plan an experiment that I am to analyse for my work. What we are going to do is to investigate the affects or the variables have on different lengths of constantan wire. I am going to use different lengths which will provide me with a range of results. The reason I want a range of results is so that I can compare and analyse results, which will let me evaluate the readings clearly. First I will tell you a little about how I started. We were set into groups with other pupils, and then together we set out and did our preliminary experiment. The preliminary experiment is very important, because it is like a practice for the real thing. Also it helps as here you can make mistakes, so when doing the real experiment errors can be eliminated. I will explain how we did the preliminary experiment and include all the steps we took.

For my introduction I want to start off by just explaining a little about the material that we are using, as this is vital so we know what is harmful and what is not, which can help with safety.

The power supply – we will be using one of these. This can be dangerous if not used safely. We should know that the power supply should not b left on for more than a few seconds, with certain wires, as it can blow the system. When plugging the plug in, you must make sure the switch is off. This may sound obvious, but is a safety regulation. Also you should never plug the plug in to the socket if your hands are wet, as you may end up experiencing an electric shock.

Middle

30

1.67

0.63

2.651

20

1.64

0.70

2.343

10

1.43

1.35

1.060

C38

SWG – 36

Diameter/Thickness – 0.20mm

At 2 Volts

 Length (cm) Volts (V) Amps (A) Resistance (Ώ) 100 1.90 0.11 17.273 90 1.87 0.12 15.583 80 1.85 0.13 14.231 70 1.71 0.14 12.214 60 1.82 0.18 10.111 50 1.83 0.20 9.150 40 1.75 0.28 6.25 30 1.71 0.33 5.182 20 1.60 0.42 3.810 10 1.52 0.72 2.111

C44

SWG – 24

Diameter/Thickness – 0.56mm

At 2 Volts

 Length (cm) Volts (V) Amps (A) Resistance (Ώ) 100 1.48 0.72 2.056 90 1.42 0.77 1.844 80 1.27 0.86 1.477 70 1.36 0.95 1.432 60 1.30 1.05 1.238 50 1.22 1.19 1.025 40 1.13 1.37 0.825 30 1.02 1.61 0.634 20 0.85 1.95 0.436 10 TOO HIGH To Calculate

C42

SWG – 28

Diameter/Thickness – 0.40mm

At 2 Volts

 Length (cm) Volts (V) Amps (A) Resistance (Ώ) 100 1.69 0.35 4.829 90 1.68 0.40 4.200 80 1.58 0.45 3.511 70 1.58 0.52 3.038 60 1.52 0.62 2.452 50 1.45 0.75 1.933 40 1.42 0.95 1.495 30 1.29 1.23 1.049 20 1.06 1.69 0.627 10 0.84 2.19 0.384

C41

SWG – 30

Diameter/Thickness – 0.31mm

At 2 Volts

 Length (cm) Volts (V) Amps (A) Resistance (Ώ) 100 1.79 0.26 6.885 90 1.80 0.29 6.207 80 1.78 0.32 5.563 70 1.77 0.37 4.784 60 1.72 0.43 4.000 50 1.70 0.52 3.269 40 1.63 0.63 2.587 30 1.56 0.84 1.857 20 1.47 1.15 1.278 10 1.35 1.56 0.865

Below are the results for my second variable, this is the thickness or the width of the wire.

Variable – Thickness of a Wire

 Part No. SWG Diameter or Thickness in mm Volts Amps Resistance C38 36 0.20 1.75 0.23 7.609 C40 32 0.28 1.77 0.38 4.658 C41 30 0.31 1.70 0.52 3.269 C42 28 0.40 1.49 0.66 2.258 C44 24 0.56 1.22 1.19 1.025 C45 22 0.71 1.00 1.66 0.602 C46 20 0.90 0.80 2.17 0.369 C47 18 1.25 0.50 2.46 0.203 C48 16 1.60 0.38 3.02 0.126

All these experiments were done at 2V for safety reasons, using a silver wire each time to make the results fair.

I believe that I have enough data to make a conclusion; this is because I have chosen a wide range of wires to test on giving me more data. I believe that I made my test accurate by doing tiny things to my work to make it better. For example, I was extremely precise when cutting the wire to its exact measurement, so I was very precise. This would have been an unfair test if I wasn’t accurate and decided to measure free hand. That is just one example of why accuracy is vital when it comes to finding results.

I consider the results very clear, and it is easy to read. It can be interpreted and understood easily, all because the tables are clear and easy to read.  I also believe that my experiment with my group was very precise. The variables are suitably and are adequate enough to the investigation, because it is a way of measuring the resistance in a circuit, and I am investigating the affects of material on the resistance levels.

Conclusion

The procedure I use I think was very suitable, because it was very precise and clear. Finding the resistance levels helped us to analyse the data. We could see which data affected the level of resistance, and others which had no influence at all.  The method I used was testing the levels of resistance by setting up a circuit, placing the wire into the crocodile clips and then using the figures from the volt meter and the ammeter, I used Ohms law to convert the numbers in to resistance, so I think this was pretty simple and I was easy to understand.

I think the quality of the evidence is very good, thankfully I can say that I did not make any errors, therefore I can say that there were no times were I needed to identify any anomalies. I did not make many errors at all through my work, so it was a satisfactory experiment.

I believe that my experiment was suitable as I said, but there are ways that maybe I could have improved on it. For example, I believe that if I had repeated my results just one more time, then possibly I would have more data, then I can compare using the same method, but this time I will have more to compare with.

I think that my method of analysing and results were reliable, because they justified the system as the results I got, I made substantially longer. I would like to add that I did my coursework very well, and it went well towards my predictions. The positive correlation in the graphs was something I wasn’t expecting, so things like this was good, as it was different.

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