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How does the resistivity of a constantan wire change with length
Relationship between length of constantan wire and resistance
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The Relationship Between the Length of Constantan Wires in a Circuit and the Current
Aim
To investigate the relationship between the length of constantan wires
in a circuit and the current flowing through.
Introduction
============
In a conductor electrons are able to jump between atoms. However in
insulators they remain around a single atom unable to move.
Constantan, a metal, unlike most other metals is a poor conductor
although it is also a poor insulator. Being a metal it must contain
some electrons able to move, but it will also have others, which are
unable to do so.
We are going to investigate this theory using the relationship between
the length and resistance.
Method
======
We are going to measure the current as it flows through varying
lengths of constantan. It will require an ammeter for measuring.
The variable of this experiment will be the length of constantan,
which will be decreased throughout the experiment, starting with a
metre length and gradually reducing the size with the aid of crocodile
clips. The voltage will be kept as a constant so as to make the
experiment a fair test. For a safe experiment to be completed we will
be aware of the heat produced by the electricity to prevent the wire
from overheating. To avoid this hazard we will only be using the power
supply in short periods: between lengths the power will be switched
off. So as to ensure accurate readings throughout the experiment we
will take a measurement for each length three times and find the
average.
Preliminary work will be carried out prior to the investigation so as
to establish an area in which the results can be determined
acceptable.
Diagram[IMAGE]
Prediction
==========
As the length of constantan is decreased the current will increase.
This is due to the resistance on the constantan giving that it is not
a good conductor. The longer the wire the greater the resistance
resulting in a lower current.
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