To carry out the investigation, I am going to use various thicknesses of wires. These will be secured to a ruler

Method

To carry out the investigation, I am going to use various thicknesses of wires. These will be secured to a ruler making it able for us to take accurate measurements. The positive crocodile clip will be clipped on to 0cm; the negative will be moved up and down the ruler accordingly. I will take measurements every 20cm, meaning that for each thickness of wire I will end up with 5 measurements. When the negative electrode is in place every 20cm, I will need to use the ammeter to check that the current is at 0.3, I will do this by increasing/decreasing the voltage. When the negative electrode is in place at every 20cm, I will need to read the voltmeter and ammeter to record the results.

Prediction

I predict that the smaller thickness of wires will have a greater resistance than the larger ones, this is because as the thickness of the wire increases, there is a larger amount of space in which the electrical current can travel. Meaning that the atoms will not be as close together as in a smaller wire. The largest thickness of wire will have the smallest resistance. I also predict that as the length of wire increases, the resistance will also increase. The electrical current has to be passed along from atom to atom. If there is a larger amount of atoms present in the wire lengthways, then the current will have to pass through a larger amount of atoms. This means that the resistance of the wire will increase. If the length of the wire is doubled, the resistance across that wire will also double. If the temperature of the wire were to be increased, the resistance would also increased. This is because heat energy causes atoms to vibrate more often, these vibrating atoms disturb the movement of the electrical current therefore a higher temperature would cause an increase in resistance.

0.31 mm

Length (cm)

20

40

60

80

00

Voltage

0.38

0.76

.16

.6

.96

Current

0.3

0.3

0.3

0.3

0.3

Resistance

.27

2.5

3.9

5.3

6.5

Voltage

0.5

.03

.51

2.02

2.55

Current

0.4

0.4

0.4

0.4

0.4

Resistance

.25

2.58

3.8

5.05

6.38

Voltage

0.64

.27

.9

2.55

3.2

Current

0.5

0.5

0.5

0.5

0.5

Resistance

.28

2.54

3.8

5.1

6.4

0.28 mm

Length (cm)

20

40

60

80

00

Voltage

0.52

.07

.6

2.09

2.68

Current

0.3

0.3

0.3

0.3

0.3

Resistance

.7

3.6

5.3

7

8.9

Voltage

0.69

.4

2.1

2.82

3.5

Current

0.4

0.4

0.4

0.4

0.4

Resistance

.7

3.5

5.25

7.05

8.75

Voltage

0.86

.76

2.6

3.48

4.38

Current

0.5

0.5

0.5

0.5

0.5

Resistance

.7

3.52

5.2

6.9

8.76

0.23 mm

Length (cm)

20

40

60

80

00

Voltage

0.73

.48

2.18

2.96

3.6

Current

0.3

0.3

0.3

0.3

0.3

Resistance

2.4

4.9

7.3

9.9

2

Voltage

0.97

.93

2.98

3.9

4.8

Current

0.4

0.4

0.4

0.4

0.4

Resistance

2.4

4.8

7.4

9.8

2

Voltage

.21

2.47

3.67

4.86

5.98

Current

0.5

0.5

0.5

0.5

0.5

Resistance

2.4

4.9

7.3

9.7

2

Evaluation

I think the way in which we carried out the investigation made the results easy to record. By doing 3 different currents on each thickness of wire, we received a range of results, and this allowed average to be taken of the results. This also means that we can plot graphs to show the trend occuring throughout the different thickness of wires. By doing this we ensure that the conclusion we come to after doing the investigation is accurate. The only real problem was in trying to get the current to be equal, as in the beginning it was hard to gauge what voltage would be needed to keep the current steady. However after a few measurements it became easier to judge. Setting up the equipment was extremely easy, as we had a circuit diagram. By using this it was easy to ensure that all the equipment was in the correct place.

The results prove what I thought would happen. By reading the results it is possible to tell that as the length of the wire was increased, the resistance increased. This was again due to the amount of atoms the electricity had to pass through before reaching the end of the wire. All three thickness show that the length of the wire affects the resistance. The results also show another part of my prediction to be correct, as the thickness of the wire is decreased, the resistance through it increases. This is because in a thicker wire, the electrical charge is more spread out than in a smaller one, therefore the resistance of that wire will be smaller than a wire where the charge is in a smaller space. If I were to repeat the experiment, there are two things that I would change. I would alter the way in which the length of the wire was measured. By using the crocodile clips to alter the length of the wire used, it was possible for an error to be made. At times the crocodile clips slipped across the wire, meaning that the wire had to be constantly watched to ensure that the correct length of wire was being measured. The second thing that I would change if the experiment was repeated is the thickness of the wires used. I would use more wires, with larger differences between the thickness of them. This will ensure that the results we receive are reliable. Also by using more wires we are making sure that the results we end up with are more representative of the actual experiment.