It was concluded from the experiment that the resistivity (r) of the
wire is 5.2 ´ 10 –7 ± 7.3 ´ 10 –10 W m. Evaluation: - The actual value for the
resistivity is 4.7 ´ 10 –7 W m. The resistivity value from the experiment is 5.2
´ 10 –7, which is close to this value. - Resistivity is dependant on temperature
and the temperatures in which these values were measured are not known. Since
the uncertainty of the experimental value is very small, the difference between
the values may be due to the temperature difference in which they were found. -
Also, the purity of the metal wire is unknown. The metal may not be completely
pure; there may be impurities in it and the experimental resistivity value may
be different from the actual value because of this. - One of the uncertainties
in the experiment was that it was very difficult to measure the length of the
wire accurately. The wire was not straight and it was very hard to straighten it
since it was very rigid. A new, straight wire should be used in order to avoid
this inaccuracy. - The diameter of the wire was also difficult to measure
because of the shape of the wire.
Since it was twisted, it had dents in some
parts and this made the reading inaccurate. This can also be avoided by using a
straight wire and taking measurements from different parts of the wire. - In
addition, the wire was not connected properly to the circuit since the crocodile
clips touched only some parts of the wire. There should be better contacts to
the wire; the wire should be surrounded completely. Soldering the contacts to
the wire will minimize this uncertainty.
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