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An investigation into how the length of the resistor will affect the resistance.

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Introduction

An investigation into how the length of the resistor will affect the resistance.

Aim: In this investigation I am going to find out how the length of the resistor  

          affects the resistance.

Resistance is the ability of an object to resist the flow of current. The value depends on the resistivity of the material from which the object is made from, its shape and size.

Factors I can change

Cross sectional area: Investigations show that the larger the cross sectional area the lower the resistance. This is because larger cross sectional areas offer more pathways for the electrons to collide with atoms and release new electrons.

Material: It is found that some materials have atoms that hold onto their electrons. These will need a lot of energy to release them for the current to flow, so affecting resistance.

Temperature: As a wire is heated, atoms in it will vibrate because their energy is increased. This causes the atoms to obstruct the pathway of electrons so increasing the resistance.

Length: The electrons have further to travel and in doing so will encounter more obstructions. These will cause the electron to loose energy, slowing the electron flow and so increasing the resistance.

TYPE                   THE ONE…       QUANTITY        UNIT               MEASURED

Independent      I change                wire length         cm                   meter ruler

Dependent        that changes          resistance           ohms (     )       resistor

...read more.

Middle

My formula for working out the resistance is:

Results

Length of wire (cm)

Voltage (V)

Current (i)

try 1

try 2

try 3

try 1

try 2

try 3

20

1.09

1.10

1.08

1.25

0.99

0.99

30

1.34

1.35

1.38

0.69

0.73

0.77

40

1.53

1.55

1.54

0.58

0.52

0.61

50

1.66

1.65

1.66

0.53

0.51

0.51

60

1.68

1.71

1.72

0.47

0.46

0.46

70

1.77

1.79

1.78

0.40

0.40

0.40

80

1.81

1.84

1.82

0.36

0.37

0.36

90

1.88

1.89

1.87

0.33

0.33

0.32

100

1.92

1.91

1.92

0.30

0.30

0.31

Above: A table with three voltage readings and three current readings for each length of wire.

Below:

...read more.

Conclusion

(Current ‘energy’ absorbed by more atoms)

Evaluation

The resistance for 20cm is the only result that isn’t really on the line of best fit. I think this could be because my first reading for this result has quite a big difference from the other two tries compared with all my other results.

I think the method I chose for this investigation was a good one as most of my results are very close together showing consistency and all are grouped very closely around the line of best fit.

Although I quickly switched off the power pack after recording my results to prevent the wire from heating up and affecting my results if I did the experiment again I would leave it for 10 minutes and not 5 because then there would be no chance of the temperature affecting my results as I probably got some slight errors.

I could also do more than three tries and get a more accurate average.

I would do this experiment at 2 Volts and 4Volts as well to make sue my results were the same for every voltage.

I could also try different lengths up to 200cm to see the length of the wire continues to be directly proportional.

...read more.

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