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An Investigation into How well Wires Conduct Electricity

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An Investigation into How well Wires Conduct Electricity Scientific Background Electricity is a form of energy; it is also very easy to use because it can flow along wires to wherever it is needed. It is a flow of negative electrons. We call this flow an electric current. The flow is measured in units called amperes or amps. 1 ampere is a flow of about six million, million, million electrons per second past each point. Voltmeters are used to measure the potential difference or "voltage" this is an electrical energy difference. Electricity can flow through a metal, such as copper, because the metal contains electrons that are free to move from one atom to another. We will be able to measure how well a wire conducts electricity by measuring the resistance. Resistance is a measure of the opposition of a component to the flow of current through it i.e. how hard it is for current to flow. The current, however, tells you what is flowing when there is a given voltage, which is why it is better to use resistance. Also if the current flowing through the wire was constantly changing then it would be impossible to get an accurate idea on what the resistance was as there would be different amounts of electrons flowing through the wire and so resistance would change because there would be different numbers of electrons trying to get through the atoms and the true resistance could never be calculated. The thin wire in a lamp tends to resist the movement of electrons in it. We say that the wire has a certain resistance to the current. The greater the resistance, the more voltage is needed to push a current through the wire. ...read more.


The more difficult it is for the electrons to move the higher the resistance. Therefore the longer the wire is, the more atoms there will be to collide with so the electrons will be slowed down more, meaning that it is harder for the current to flow (i.e. the resistance is higher). Method: 1. Set up the apparatus as show in the diagram above. Make sure that when the wire is in the circuit it does not coil round and cross over itself as this could decrease the length of wire that the current has to flow through and in doing so will make the results inaccurate. 2. Using your first selected length of wire (in this case 25cm), set the voltage to 0.5V (or as close as possible) then record the reading shown on the ammeter (this is the current) you then use the formula (resistance = potential difference � current) to fill in the resistance column. It is important to record all the readings you take. 3. To enable you to repeat the experiment so you can get a sensible average, you should set the voltage to 1.0V (or as close as possible) and record the new reading on the ammeter and again work out the resistance. These two results for resistance should be about the same. However even if this is the case it is always best to get at least three results for each length so you can be sure that you are getting sensible readings. 4. After you have collected a minimum of three results for the first length of wire, move the crocodile clips along so that the length of the wire is now 35cm. ...read more.


I would do this by monitoring all the factors much more closely. I would use instruments/equipment that would allow me to make sure that every other factor did stay absolutely constant, such as a temperature sensor to record even the slightest change in the wire temperature and small measuring device to make sure that the wire is the same thickness all the way through, so as not to make the test unfair by having the wire different thickness, which could make it easier for the electrons to pass through if it was thicker and so not give an accurate resistance result. I think that even though we didn't have any equipment to notice slight changes in wire temperature, thickness, etc. I think that overall our experiments were accurate enough to make an certain conclusion, as all our experiments gave very similar results as you can see in the results table and there weren't any glaringly obvious errors or differences between them. I think that with the equipment we had we managed to carry out a very accurate experiment and produce an accurate conclusion and evaluation. We could do more work to take the investigation further, such as increasing the length of wire we use or shortening the intervals between recording, such as taking results every 5cms instead of every 10cms. We could also use several ammeters to see if any of the current is lost as it passes through the wire or several voltmeters to see if the potential difference changes at different points on the wire. This, as well as adding "extra-sensitive equipment" would all add to making the results more accurate and we would be able to give a definite, firm conclusion due to the sheer volume of results we would have and how accurate all these would be. Page 1 of 10 Lucy Blackbourn ...read more.

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