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Investigate factors affecting the resistance of a wire.

Extracts from this document...

Introduction

Dino Sabnani                                 Physics Coursework                20th September 03

Aim-

To investigate factors affecting the resistance of a wire.  There are a plenty of things I can alter which will change the resistance of a wire such as the voltage/ length of the wire, the thickness of the wire and the temperature of the wire.  Most of these are quite impossible to change.  However an easy one in which we can alter easily and receive accurate results would be the length of the wire.  The things in which I will control will be things such as the thickness of the wire, material and voltage or current. I have picked Constantan as the wire for this investigation.  You will see later in the preliminary work why I have chosen this material.

Hypothesis-

After doing some research and using some scientific knowledge.  I have come to a conclusion that an increase in the length of wire is an increase in resistance.

Electrons carry charge. But the charge each electron carries is extremely low. So there are millions and millions of electrons flowing through a circuit. More electrons per second mean more current. The current is calculated by .I equals current, Q is charge and T is time.

When the length of the wire increases, the electrons will have to pass through more and more atoms in the wire.  More collisions will happen, this means that there will be more electrons bumping through the atoms in the wire.

Middle

28

0.24

0.48

1.75

30

0.19

0.36

1.47

32

0.16

0.29

1.03

36

0.07

0.14

0.59

Copper

28

4.17

4.78

5.55

30

2.9

3

3.03

32

2.1

3.19

5.35

36

2.83

3.3

5.04

Constantan

28

0.58

1.05

3

30

0.42

0.74

2.23

32

0.32

0.46

1.66

36

0.15

0.29

1.1

As we can see from the experiment our experiment will work because the current passing through each of the wire is increasing as the length of the wire is shortened.

For my experiment I will use Constantan,  This is because it gave me the widest

Conclusion

Comment of the overall experiment-

Overall, I feel that the experiment was done in a quite good state.  Yes there were 1 or 2 anomalous results; however the line of best fit still turned out as expected.  10 results is good enough for us to draw a decent and accurate line.  All in all most points lie very closely to the line of best fit.  The line is quite reliable as it turned out as expected (i.e. it matches my prediction) and it also matches the research I had done previously.  It shows us a general pattern of the length of wire and resistance being proportional.

Things I could have done better-

The experiment could have been done much more accurately.  I could have used a more reliable ammeter and voltmeter so readings can be more accurate, they can be more stable and corrected to more decimal places, in this case there will be fewer errors in the graph.  We could also have used fewer wires.  The wires we use have a very slight resistance, therefore affecting the experiment slightly.

Besides all this there is not much else we could have done.  The experiment could have turned out better if the equipment used was much more advanced (explained above).  However as said earlier the results are good enough to show me a general pattern and allow me to analyse what happens.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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