The Relationship Between the Length of Constantan Wires in a Circuit and the Current

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The Relationship Between the Length of Constantan Wires in a Circuit and the Current


To investigate the relationship between the length of constantan wires

in a circuit and the current flowing through.



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.



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


Preliminary work will be carried out prior to the investigation so as

to establish an area in which the results can be determined





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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