In this investigation I am going to investigate the resistance in a piece of wire. Resistance is the opposition to the flow of current and is measured in Ohms.

        I am going to change the length of the wire but keep the material of the wire, the temperature of the wire and the area or thickness of the wire all the same to make it a fair test.

        I think that the shorter the wire the less resistance.  I think its because the longer the wire the more molecules there is to get past for the current therefore the shorter the wire there is less molecules to get past.

                

                    Molecules

              Length        

                Current of electrons

Apparatus

 

                                               Measuring device

        3 wires

        Mutlimeter

Method

First we got all the apparatus and set it out.  The multimeter gets turned to the right setting to measure resistance then the two connecting wires in the bottom hole and the second hole.  We started from 0cm to 10cm then kept one wire on 0cm and the other gradually moving up 10cms each reading.  Each reading will be taken three times then an average at the end.

Results

                               Resistance in Ohms (Ω)

Length of wire                 1                      2                      3                       Average              

10cm                   1.8        1.9               1.9         1.9 Ω

20cm                   3.0        2.9                   2.8        2.9 Ω

30cm                   4.0             4.2                   4.1        4.1 Ω

40cm                   5.3             5.2                   5.2        5.2 Ω

50cm                   6.6          6.8                   6.6        6.7 Ω

60cm                   7.8        7.9        7.4        7.7 Ω

70cm                   8.8        8.7        8.7        8.7 Ω

80cm                   10.0        9.9        9.8        9.9 Ω

90cm                   11.1         11.0        11.2        11.1 Ω

100cm                 12.3        12.2        12.3        12.3 Ω                

Conclusion

A length of wire is made up of molecules, which act as an opposition to the flow of electrons.  The longer the length of wire the more molecules there are to oppose the flow of electrons, this resulted in a higher resistance.  The Shorter the length of wire the less molecules there are to oppose the flow of electrons, this resulted in lower resistance. If the wire is half the length of a certain wire, it would have has half the number of atoms, this means that the electrons will collide with the atoms half the amount of times. In addition, if the length of the wire was trebled or quadrupled, then the resistance would also treble or quadruple.

Evaluation

        I think my method was quite a good method but if I did it again I would use crocodile clipped wire instead of just straight wires that made the readings less accurate because I had to hold the wire to the wire that measured the length and my hand could have moved, this could also make it an unfair test.

        My results and data were very reliable because I redone each experiment three times then found the average of each length.  I can trust this to support an accurate conclusion.  There are not any very anomalous results except the 50cm length of wire was just a little bit out but apart from that the experiment was a success.