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What factors affect the resistance of a wire?The reason why the length of the wire affects the resistance of the wire is because if there is more wire for the electrons to travel down, they are impeded by more stationary atoms

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Introduction

Aim: I am going to find what factors affect the resistance of a wire.

What is resistance?

The electrical resistance of an object is a measurement of its opposition to the passage of electric current. This relates to ohm’s law;

The resistance of a resistive object determines the amount of current through the object for a given potential difference across the object, in accordance with Ohm's law:

image00.png

The basics of Ohm’s Law

In electrical circuits, Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them, provided that the temperature remains constant.

The mathematical equation that describes this relationship is:

image01.png

Factors

The resistance of the wire depends on the amount of atom particles in the wire that can impede the flow of electrons – this is resistance. There are four main factors that affect the resistance of a wire; the length of the wire, the thickness of the wire, the material the wire is made of, and the temperature of the wire.

The reason why the length of the wire affects the resistance of the wire is because if there is more wire for the electrons to

...read more.

Middle

0.57

0.58

0.59

0.58

8.069

Nichrome 26swg

10cm

0.62

0.60

0.62

0.61

3.66

3.58

3.61

3.62

0.169

40cm

0.69

0.72

0.70

0.70

1.44

1.45

1.43

1.44

0.486

70cm

0.86

0.86

0.84

0.85

0.87

0.87

0.86

0.87

0.977

Tinned Copper 20swg

10cm

0.07

0.06

0.07

0.07

8.18

8.17

8.19

8.18

0.009

40cm

0.13

0.14

0.14

0.14

8.44

8.44

8.45

8.44

0.017

70cm

0.20

0.20

0.21

0.20

8.34

8.34

8.34

8.56

0.023

Here are the results from these tests

From these results I concluded that I would use constantan because I found the readings constant as well as being high enough to make good sized graphs with and this would make the results reliable and more presentable.

Main Test

Using the results from my preliminary test I have decided to use the constantan wire at intervals of 10cm ranging from 10cm to 70cm as this will make for a wide range of results on my graphs.

Method

  1. Set up the circuit as shown early in this investigation
  2. Cut the wire of constantan to 70cm and insert in circuit
  3. Set the power pack to 5V
  4. Turn circuit on and write down measurements of voltage and current readings
...read more.

Conclusion

My conclusion is representative of all my data as they all showed the same conclusion so I had to remove no results. I believe my results covered a wide enough range to give an accurate conclusion that is representative of most, if not all data. All of this data is reliable and accurate so I can say this is a firm conclusion.

Evaluating my method

I had no problems with my method, the equipment I used was chosen for accuracy so I knew my results would be representative. Throughout the experiment I controlled the other factors that can affect the investigation; I controlled temperature by using 28°C (room temperature) and carefully watching a temperature gauge throughout. Another factor I had to keep constant was voltage, therefore before each test I checked the voltage coming out of the battery box with my multimeter. To control the density of the wire I used the same wire throughout the main test. I feel my results were very accurate as I used instruments to give me results instead of judging by eye which would have been the problem with the ammeter. On my multimeter I used an appropriate scale division so the readings were adequate to the correct amount of decimal places.

Reliability of conclusion

To check my conclusion were totally correct, I cross-referenced my results with two other scientists.

Bibliography:

  • http://scienceaid.co.uk/physics/electricity/images/ohmslaw.png

...read more.

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