Effect of length of a conducting wire on resistance

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Sarah Webb, Year 10. Physics Coursework.

“Effect of length of a conducting wire on resistance.”

Prediction:

I predict that as the wire gets longer then the resistance of that wire will become higher. This will occur because as the length of the wire increases the free-moving electrons which carry the charge will have to bypass more atoms as they flow towards the positive terminal.

In order to prove my prediction I will be using this circuit                         

Apparatus: Ammeter, voltmeter, wires,

                                Cells and a length of the wire that I

                                Will be testing. I will choose this

                                Wire during my preliminary work.

I predict that the graph of my results will look something like this:

Because as the wire becomes longer the resistance will increase.

Aim: To investigate how the length of a piece of conducting wire affects it’s resistance.

Background Knowledge:

In order to send an electrical current through a component there needs to be a certain amount of voltage (Potential Difference) In order to force the current through the component. The Resistance of a component (or wire) is how high the voltage must be in order for the current to get through the wire.  Resistance, voltage and current are connected through this equation: resistance=voltage/current. As the voltage increases so does the resistance, if the current increases then the voltage decreases and so, in turn does the resistance.

        

Controlled Variables:

The factors effecting my investigation are:

Thickness of wire: This will effect the resistance of the wire because as the wire becomes thinner then the electrons find it harder to fit through the wire depending on how thin it has become, as there are lots of electrons they have to move closer together to fit through the smaller space and this causes them to slow down more. The thinner the wire becomes then the higher the resistance will be. If the wire is wider then the electrons can spread out as they travel down the wire, this means that there are less collisions between the metal atoms and the free-moving electrons, and the electrons can travel down the wire faster, resulting in a lower resistance (and also a lower voltage is needed to push the atoms through the wire.)

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Type of wire: When I have chosen the wire I will be using (during my preliminary work) I will use this wire continuously throughout my investigation, as other different types of wire may have a different resistance to the one I have chosen which would distort my results.

Temperature: The temperature will have to be kept roughly the same as the atoms within the metal move faster if the temperature is hotter, this means that the free electrons inside the metal will be moving faster than they would originally be on a cooler day. If the atoms are moving quicker ...

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