Copper, Constantan, Manganan and Nichrome - which is the best conductor?

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Copper, Constantan, Manganan and Nichrome - which is the best conductor?

Background Knowledge

Conduction of electricity in metals requires a potential difference across two ends of a conductor for it to occur. This causes a flow of electrons in the wire, more commonly known as a current. The electrons in this current are free, meaning they are can move around in the wire freely. The number of free electrons depends on the wire. The more free electrons the better a conductor it will be. The electrons may however come up against some resistances while flowing in the current. Resistance is the result of energy loss as heat. These resistances or obstacles, which slow the electrons down, are other electrons and the fixed particles of the metal i.e. atoms. These slow the electrons down because while they are flowing freely they collide with the other electrons and the fixed particles. These collisions convert some of the energy that the free electrons are carrying into heat.

The resistance of a length of wire is calculated by measuring the current in the circuit (in series) and the voltage across the wire (in parallel). Then the resistance can be found by incorporating these values into this formula: -

R = V / I

Units

V = Potential Difference (Voltage) measured in volts

I = Current measured in amps

R = Resistance measured in ohms

It is also required to know of Ohm's Law, which states that "The current through a metallic conductor is directly proportional to the voltage across its ends if the temperature or other conditions are constant." This means that the resistance of a metallic conductor is constant providing that the temperature also remains constant. Furthermore, as temperature increases the resistance of a metal also increases. This is because as the temperature increases, the particles gain more energy and are therefore moving around more quickly. This increases the chance of collisions with the electrons.

Prediction

I think that copper wire will be the best conductor. The copper wire I will be using is pure copper. Pure copper is used widespeadly in wiring, and surely it must have a low resistance for it to be used all over the world.

I think manganin wire will be the next best. It is an alloy containing 80% copper, 13 - 18% manganese and 1 - 4% nickel. This isn't pure copper so it won't be as good a conductor as the copper will be.

Constantan, which is also an alloy contains 60% copper and 40% nickel. This has less copper again therefore constanan will be a worse conductor than both pure copper and manganin.

Nichrome contains 20% chromium and 80% nickel. It has no copper in it so it will be the worst conductor of them all.

(I used the book "Tables of Physical and Chemical Constants" by Kaye and Laby to gather this information.)

In brief, I predict that the copper that is present in the piece of wire, the lower the resistance will be. The wire with the lowest resistance will be the best conductor.

Variables

These are anything, which can affect my investigation and results.

Independent Variables

These are variables that have to be changed. I will have to change the type of wire, which I am measuring the amperage from each time, to see which has the lowest resistance. I am using four different metal wires, these are: -
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* Copper

* Nichrome

* Constantan

* Manganin

The voltage will also change because I will be setting it at different levels each time. The voltage will be measured in volts.

Dependant Variables

These are what I am going to measure in the investigation. During my investigation I will be measuring the ammeter. I chose to use it because it is a lot more accurate a digital meters, which was also available. The ammeter shows me the current in the wire and current is measured in amperes or amps for ...

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