How Does the Diameter of a While Affect the Resistance in a Circuit

Topics: Electric current, Ohm's law, Electron Pages: 7 (1602 words) Published: February 16, 2012
How Does The Diameter Of Wire Affect The Resistance In A Circuit?

Some metals such as copper, silver and gold are very good conductors of electricity. This is because they all have only one electron on the outer shell. This means that they need only a tiny amount of energy in order to allow the electron to move. Non-metals, however, do not have free electrons, so even non-metals that only have one electron on their outer shell can still hold onto them tightly.

Aim Of The Investigation:
The aim of the investigation is to find out if there is a link between the thickness of a wire and resistance in a circuit.

Ohm’s Law:
Ohms law uses the formula of dividing the Voltage (V) by the current (I), then whatever the outcome of that is, is the resistance (R). For example Voltage = 4, Current = 2.65, 4÷2.65 = 1.509, therefore the resistance (R) = 1.509. We will use this formula in our experiment to find the resistance of the different wires and then once we have 3 different resistances from the given wire, we will work out the mean, in order to have a reliable answer with us, having removed any outliers the experiment may show.

Model Of Resistance:
Resistance measures a materials opposition to the flow of electric current. An example of a model of resistance is a motorway. For instance, if all the lanes are open on the road, there will be a steady flow and speed of the cars that are travelling on it. However, if there was to be an accident and now only one lane was open, the flow of traffic would be much slower, due to the fact that all cars are now travelling down one lane, as opposed to three or four. The same principle applies for the current of electricity.

There are a number of variables that will affect the resistance of a wire. Of those shown below, the first four will be examined as part of this investigation.

Length Of Wire:
This will affect the resistance, as if the piece of wire is very long it will take the current a long time to pass all the way through of it, whereas if you have the piece of wire too short, then there will be no resistance and it will not work.

Thickness Of Wire:
This will affect the level of resistance, as the wider the wire is, the faster the flow of electrons can pass through, whereas on the other hand if the wire is very thin, then it will take longer as the electrons will have a smaller area to travel through.

Temperature Of Wire:
This will affect the resistance, as if the wire was to be heated then it would cause the particles in the wire to vibrate more, making it harder for the electrons to pass through, whereas if the wire was to be cool then we would not encounter this problem.

The way in which this affects the level of resistance is that the higher the voltage, the hotter the wire will get. This will force the resistance to be higher and therefore possibly making the results unreliable.

Composition of the Wire:
The materials of which the wire is made will alter the resistance. Wire used in magnets is made from copper while wire in heat elements such a kettles is made of an alloy of Nickel and Chromium. These two types of wires will have differing resistance, with all other factors remaining equal.

My Prediction:
My prediction is that the thicker the wire is, the lower the resistance will be. This is because the wider the larger amount of space, this will allow for the electrons to move more freely through the wire. The thinner the wire, the less room the electrons will have to move through it, so it will therefore take longer for it to pass through.

Preliminary Experiment:
In order to keep our test fair, we needed to have the same length of wire and keep the same voltage. We did a preliminary experiment in order to find out what would be best to use for our final investigation.

● Firstly we cut 3 different lengths of wire, 10, 20 and 30 cms. ● Secondly we connected each wire to a power...
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