I predict that the longer the wire the more resistance because the electrons have further to travel.

  The results that I collected are on the results table. I got the resistance by dividing the voltemeter reading by the ammeter reading.

Valid and reliable

  This experiment was valid because we used the same equipment each time and did the same procedure and collated the information in the same fashion.

  The results were not reliable because there are errors that I have circled on the graph. This could be down to us not waiting long enough for the wires to cool down also the points at which we took the readings might not have been exactly 10cm apart.

Results                   At 50cm              At 100cm              Ratio

Thick

Medium

Thin

All the ratios would have been 2 (doubled) if the experiment was more accurate. This proves that the resistance and thickness is directly proportional to resistance, the longer the wire the more resistance and the thicker the wire the less resistance and you can see this from the graph.

Conclusion

  I think overall the experiment went well and I got the relevant information needed to prove my hypothesis. I proved my hypothesis and have shown this in the graph but there might be some errors in the graph that I have circled. I think I could have made the experiment even more reliable if I had done it three times and fund the mean of the resistance. Also if we have had longer then I would have been able to make sure that the equipment had cooled down and was the same for each testing. We could have also got the class to put are results together making an even more accurate results table, the only problem with this is that different peoples equipment may have been different and therefore given different readings. I think the graph clearly shows evidence that length and thickness of the wires is directly proportional or indirectly proportional to the resistance, the length is directly proportional to the resistance because the further the electrons have to travel along the wire the more chance they have of colliding with metal ions and loosing energy which will increase the resistance. You can also see that the resistance is inversely proportional to the cross sectional area this is because the bigger the cross sectional area of the conductor, the more free electrons there are to care the electron charge along the wire therefore lowering resistance.