Apparatus
Meter rule
Micrometer
Multimeter
3 wires (Copper, Nichrome, Constantan)
2 connecting wires + 2 crocodile clips
Planned method
I shall firstly measure the length of the given wire to the nearest mm using a ruler. I will then measure the diameter of the wires using a micrometer my calculations will be recorded in mm. After revising my plan I have decided to repeat my diameter measurements and resistances record three times for each wire so that I can find an average and use this recording later. This will hopefully eliminate the error magnitude. I will then measure the resistance of each of the wires in ohms using a multimeter this will be done by connecting crocodile clips to the ends of the wire. I shall keep records of my data in a table as I carry out the experiment. After finding the diameter and resistance of the wires this will enable me to find the resistivity of the wires.
The possible errors that could be involved in the experiment are the diameter of the wires. As the measurements were rounded of to the nearest mm the magnitude of error can also be calculated
In copper
0.275mm was the first reading I collected
Meaning the max reading would be = 0.2755
And the minimum being = 0.2745
Therefore 0.275mm (+or-) 0.0005
Absolute error = 0.0005
% error = 0.0005 x 100
0.275
=0.182% (3.s.f)
(My results and tables can be found on a separate piece of paper)
The comparison of my results and the text book results
Copper
The value I calculated using my data was
= 1.41 x 10-7
The most common value found in text books
= 1.72 x 10
(1.41 x 10-7) – (1.72 x 10-8) x 100
1.72 x 10-8
= 1.238 x 10-7
1.72 x 10-7
=7.19 x 10-15 x 100
=7.1900000000000 % magnitude error
This percentage in error is not that large compared to the large difference in conditions when the experiment was being carried out. When conducted in a proper laboratory being accurate is more essential and so the apparatus used is of higher accuracy than the one that we were able to use. When we were recording the length of the wire we used a ruler this may not have been as accurate as expected.
Copper is not the best conductor, however.
Silver is better and Gold is better. These are
expensive metals and are used in special
applications only.
There is also a group of materials that are
specially created that are not conductors until
certain impurities are added. Then they
become very good conductors, better than any
naturally occuring materials.
Also, cooling materials down to near absolute
zero (Kelvin) make some of them nearly
perfect conductors. At such a low temperature
the atoms no longer vibrate and electrons are
free to move.
I don't understand your experiment though.
What did the wax melting prove? A better
conductor generates less heat when carrying
electrical current.
Gus
Conclusion
Copper is the best conductor of the three metals. This is mainly because the electrons in copper can be more easily transferred from one to another. This is important because electric current is based on the flow of electrons through the conductor.
