In this experiment the resistance change in a wire will be investigated. I will be investigating if the thickness or cross-sectional diameter of the wire affects the resistance.

Diagram

Method

• Set up the apparatus as shown above.

• Measure a piece of wire to 50cm

• Clip on the crocodile clips at each end

• Turn the power pack to 12V

• Now write down the readings from the voltmeter and the ammeter

• Repeat with different thickness’ of wire

• Repeat the whole experiment 5 times so an average can be taken

• Work out the resistance (R=V/I)

Fair testing

        To keep my experiment a fair test I will bee using the same equipment and making sure that the length of wire I use stay the same length. I will also keep the power pack at 12V on all experiments

Prediction

I think that when I increase the thickness of the wire, the resistance will be lower.

Scientific Explanation

When a wire has a larger diameter, there is more room for electrons to pass through so therefore if you have a smaller wire there is less room for electrons to pass through. This is due to metal atoms inside the wire. Electrons need to be able to flow through the gaps in the metal atoms to create a current and form a circuit. When the wire is thick there are bigger gaps between the metal atoms so therefore more electrons can pass through to make the circuit complete. This is the opposite for thin wire, where there are fewer gaps for the electrons to pass through therefore making it harder to complete the circuit.

Preliminary experiment

We need to do a preliminary experiment to see if anything needs to be changed for the final experiment.

Modifications after Preliminary Experiment

The results from the trial experiment were fine so I don’t need to change anything for the final experiment.

Results

Exp. 1

Repeat 1 

Repeat 2

Repeat 3

Repeat 4

Averages

Analysis

From my results, you can see that as the thickness of the wire decreased, the voltage increases by a lot. From all the tables, you can see a linear correlation and there doesn’t seem to be any anomalies

        

Conclusion

I think that my experiment went well as there is a clear result from it. You can see that as the thickness of the wire decreases, voltage goes up; therefore there is less resistance. This has been proves earlier in my prediction, because there are bigger gaps between metal atoms in a thicker wire so electrons can flow more freely.

Comparison with Prediction

I said in my prediction that “I think that when I increase the thickness of the wire, the resistance will be lower.”

When comparing this to my conclusion I can safely say that my hypothesis was correct as I achieved a good set of results.

Quality of my Results

I thought I had quite good results from my experiment as I didn’t get any anomalies, even when I did 5 repeats, so I must have put in a good effort in the experiment.

My experiment went well with no problems because I made it a fair test and didn’t mess around.

Improving my Experiment

I could do more repeats.

I could use more thicknesses of wire.

I could use a different voltage going in to the circuit.

I could calculate the resistance using ohms law.

Further Investigations

   I could try doing the same experiment but keeping the thickness of the wire the same, and changing the length instead