Provided the temperature of the wire does not change, the resistance should be the same for each reading at the same voltage and length of wire. This is the circuit I will use: I will 32swg copper wire. – The thickness of the wire and type of wire shall be kept constant. The variable for my experiment is the lengths, which will be experimented at 10cm, 20cm, 30cm, 40cm and 50cm. I will test the same length of wire at 1, 2, 3, 4 and 5 Volts. Also, I will record the reading on the ammeter 3 times each, so I can find an average to make my results more accurate. The Ohms will be rounded to 2 decimal places.

I will record the results in a table like this: Length (cm) Volts Current (A) Current (A) Current (A) Average Current (A) (2d. p. ) Resistance (? ) (2d. p. ) 1 – 2 – 3 – 4 – 5 Also, to make the experiment as accurate as possible, I will turn the power supply off between readings, so the wire does not get over heated, as the temperature affects resistance, as I mentioned earlier in my plan. I am now ready for my preliminary test. These are the results: Length (cm) Volts Average Current (A) Resistance (? ) 1 The results show that resistance lessened.

Which is not what I expected. After testing the wire at 3V, the wire heated up too much and smoked. At 4 Volts, the wire turned red and eventually melted into 2 pieces. So, I decided that I would not use copper for my experiment. – Instead, I will use Nichrome 32swg, so that I can control the temperature. These are the results for my preliminary test with Nichrome: Length (cm) Volts Average Current (A) Resistance (? ) My results show that the resistance is constant if the voltage increases, for the same length of wire.

Also, as I predicted earlier, the resistance does increase proportionally: 20cm is 2 X 10cm, and the resistance for the 20cm wire is also 2 X the resistance for the 10cm wire. I think these are sufficient results for my preliminary test. The only thing I will change in my plan is the type of wire, which I have now changed from copper to Nichrome. Observation: To make the results really accurate, I repeated my readings three times, to get an average. Also to keep it very accurate, I kept my results to 2 decimal places. – This also makes my graph analysis more accurate than if I had already recorded the amperes to whole numbers.

– This would have made my average amps less accurate, and therefore, my resistance for each voltage would have been quite inaccurate. Results: Length (cm) Volts Current (A) Current (A) Current (A) Average Current (2d. p. ) Resistance (? ) (2d. p. ) 1 Length (cm) Volts Current (A) Current (A) Current (A) Average Current (2d. p. ) Resistance (? )(2d. p. ) Length (cm) Volts Current (A) Current (A) Current (A) Average Current (2d. p. ) Resistance (? ) (2d. p. ) Length (cm) Volts Current (A) Current (A) Current (A) Average Current (2d. p. ) Resistance (? ) (2d. p. ).06 Length (cm) Volts Current (A) Current (A) Current (A) Average Current (2d. p. ) Resistance (? ) (2d. p. )

Analysis: [See graphs] I have found that there is a relationship between the voltage and current; as voltage increases, the current increases too. This is true for all the lengths of wire that I experimented. After drawing my line of best for each graph, I calculated the gradient, which shows the resistance for that particular length of wire.

These are my calculations: 10cm: (to 2 decimal places) I will now plot a resistance-length graph to see whether they are proportional to each other. My graph shows that resistance is proportional to length. For example, according to my line of best fit, the resistance for a 20cm wire is 4? ; 2 times the resistance of a 10cm, which is 2?. Also, the resistance of a 40cm wire is 8. 10? , which is a tenth of an ? more than 2 times the resistance of a 20cm wire.

The resistance of a 50cm wire is 10. 10? ; exactly 2 times the resistance to that of what my line of best fit indicates the resistance of a 25cm would be, which is 5.05?. Also, the resistance of a 25cm wire is 5. 05? , which is a twentieth of an ? more than 5 times 1. 00? – the resistance of a 5cm wire. Conclusion: This all shows that my experiment proves that resistance is proportional to the length of the wire. If the length of the wire is increased, the resistance is increased proportionally.

Therefore, my hypothesis is correct. Also, I found that the relationship between the resistance and the current is inversely proportional; as the resistance increases, the current decreases. This is due to the rate of electron flow.