Investigation to how length affects the resistance of a wire.

I am going to make sure my experiment is a fair test,I am going to make sure the only variable being changed is the length. Below is a variables table

VARIABLE

CHANGE

CONTROL (keep the same?)

voltage

no

Keep the same

current

no

Keep the same

Nichrome wire

yes

no

Below is a diagram of how I will set up my experiment

Method

. I gather all the required equipment, ammeter,voltmeter,wires, crocodile clips, and set it like the diagram above

2. I am going to measure a meter of nichrome wire and stick it to a meter ruler, and complete the circuit.

3. I regulate the voltage and current with the variable resistor to make sure it won't affect my results

4. I will record the readings in the ammeter and the voltmeter calculate the resistance by dividing the voltage by the current.

5. Work out the averages and plot a graph of the results

Safety

To make my experiment safe so that neither myself nor anyone else in the labartory was hurt I used the equipment very carefully taking special care of the wire which will heat up.

I did some preliminary work to test my method and to see what sort of results I would get. This helped me to improve my method, predict my results, and also decide what range of values to measure. The results of my preliminary work are

AMP

VOLTS

LENGTH(cm)

RESISTANCE (?)

0.38

5.21

00

3.7

0.38

2.85

50

7.5

0.38

.13

20

2.9

0.38

0.03

0

.6

After doing preliminary work I have decided to take measurements between 100cm and 10 cm with intervals of 10cms, because I thought that this would clearly show any pattern/give sufficient results. These are the results for the experiments.

Test 1

AMP

VOLTS

LENGTH(cm)

RESISTANCE (?)

0.38

5.71

00

5.0

0.38

5.22

90

3.7

0.38

4.64

80

2.2

0.38

4.22

70

1.1

0.38

3.53

60

9.4

0.38

2.90

50

7.6

0.38

2.31

40

6.0

0.38

.72

30

4.5

0.38

.13

20

2.9

0.38

0.59

0

.5

Test 2

AMP

VOLTS

LENGTH(cm)

RESISTANCE (?)

0.38

5.70

00

5.0

0.38

5.25

90

3.8

0.38

4.69

80

2.3

0.38

4.18

70

1.0

0.38

3.47

60

9.1

0.38

2.89

50

7.6

0.38

2.24

40

5.39

0.38

.68

30

4.4

0.38

.13

20

3.0

0.38

0.54

0

.4

Test 3

AMP

VOLTS

LENGTH(cm)

RESISTANCE (?)

0.38

5.58

00

4.5

0.38

5.04

90

3.4

0.38

4.54

80

2.2

0.38

3.96

70

0.8

0.38

3.48

60

9.1

0.38

2.74

50

7.7

0.38

2.31

40

5.9

0.38

.71

30

4.0

0.38

.14

20

2.9

0.38

0.6

0

.2

Conclusion

My reslts support my prediction, I said that the longer the wire the resistance will increase and in my results I found out that this was correct. The shape of my graph is a straight line

I think my readings were accurate,. I repeated the experiment 3 times so the results were more reliable and accurate. When I repeated my experiments I found that the results were similar. On my graph the points are close to the best fit line, this show that there is a strong relation between . I did not have any anomalies The reason why increase in length increases resistance is because the electrons have to travel a further distance, resulting in more collisions in the wire. Overall I am happy with my resuls and they were how I expected.

I thought my method was good, if I could improve my method and experiment I would measure the wire up more accurately because it had slack also in some cases the readings on the ammeter and voltmeter took quite long to settle, if I waited longer for readings the results would be more accurate. I thought my readings had sufficient and fair intervals. Other experiments to investigate resistance could be to see how resistance affects different material wire? The amount of heat generated? Or How thickness of wire affects resistance?