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# An experiment to find how the resistance of a wire changes when the length is changed.

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Introduction

An Experiment To Find How The Resistance Of A Wire Changes When The Length Is Changed

## Aim

In this experiment we hope to see how the resistance of a wire changes when the length is changed.

## Prediction

In this experiment I predict that when the length of a wire increases the resistance will also increase. Thus length is directly proportional to the resistance.

## Hypothesis

I think my prediction is true because the equation for resistance is voltage divided by current. So the voltage and current directly affect the resistance. The resistance should be directly proportional to the length, as two 10cm wires should have the same resistance as a 20cm wire. Ohm’s law states that a current flowing through a metal conductor is directly proportional to the voltage across its ends (provided all other conditions are constant). So I know that if we add a variable – in this case length – resistance will change. I expect that the longer the wire, the higher the resistance. Electrons colliding with atoms in the wire cause resistance.

Middle

Resistance R (Ohms)

Second Current

I (A)

Second Voltage

V (V)

Resistance

R (Ohms)

5cm

0.27

0.23

0.85

0.26

0.19

0.73

15cm

0.26

0.56

2.15

0.25

0.56

2.24

25cm

0.24

0.86

3.58

0.23

0.89

3.87

35cm

0.22

1.14

5.18

0.21

1.17

5.57

45cm

0.21

1.38

6.57

0.20

1.40

7

55cm

0.19

1.60

8.42

0.19

1.61

8.47

Conclusion

To gather more relevant evidence we could have done the experiment with a different metal just to see if the resistance still went up when the length was increased. The resistance would change in this new wire depending on how many atoms were in the wire. Also we could have changed the width of the wire and I think that as the width of the wire got larger the resistance would decrease, as there would do more room for the electrons to move.

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