To find out how the length of a piece of nicrome wire Can affect the resistance of electricity in a current.

I will plot all of these results on a graph along with the

average of all the results. The reason for getting three

sets of results is that it makes your results much more

accurate. This is because you can see if you have made a mistake and because I am taking an average I will need more results to make sure it is

accurate.

I will keep this experiment fair by making sure that on each experiment I use the same voltage and the same thickness of wire. I will also make sure that the wire is straight so that when I need to measure it against the ruler my measurements will be accurate. I will use the same wires, power pack, ammeter and voltmeter each time.

To keep this experiment safe I will make sure that the voltage is not to high because this may cause the wire to melt. I will make sure I do not touch the wire because it can get hot and may burn but I am to use the crocodile clips only to change the length. Also to be careful when straightening the wire because it is very thin and may cut into the skin.

Prediction:

I predict that as the length of the wire is increased the resistance will increase and as the length is decreased the resistance will do the same. I believe this because I know that if the electrons in a current have further to travel then the resistance will increase. I also believe that as the resistance increases the voltage must increase because there needs to be more power pushing the electrons through.

Length

Voltage

Amps

Resistance (ohms)

st set of results

5cm

.62

.14

.42

30cm

.82

0.62

2.94

45cm

.80

0.42

2.9

60cm

.92

0.34

5.65

75cm

.91

0.27

7.07

2nd set of results

5cm

.59

.9

.59

30cm

.81

0.11

2.55

45cm

.83

0.40

4.58

60cm

.92

0.32

6

75cm

.93

0.26

7.42

3rd set of results

5cm

.63

0.99

.65

30cm

.84

0.70

2.63

45cm

.82

0.43

4.23

60cm

.92

0.33

5.82

75cm

.99

0.25

9.05

Analysis/conclusion:

By doing this experiment I have found out that the resistance is affected by the length of wire, I have found that as the length of wire increases so does the resistance of the current. This is shown by the fact that the graph curves up, which proves that my prediction was correct.

This is explained in ohms law, which states that the length of a piece of wire is proportional to the resistance.

Evaluation:

The procedure , I believe was reliable, but I could have improved it in many ways to get more accurate results, such as; doing the experiments more than 3 times to get a more accurate average, using a measuring device that was more accurate and using a rheostat instead of a piece of nicrome wire. There were limitations in the experiment ie. The crocodile clips are wide and therefore are not as accurate, also we set up the wire using limited equipment so it could never have been perfectly accurate. In the first set of results there were some readings that did not fit the pattern, this may have been because I did not take enough care over my measuring. This occurred again in the second set of results but not in the third, this may have been because the wire was not held in position properly and so was re-straightened before the last set were taken.