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# Does the resistance of an electrical wire depend on its length? Essay

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Does the resistance of an electrical wire depend on its length? An investigation was carried out to answer the question, Does the resistance of an electrical wire depend on its length?. To answer this I will watch an experiment and us the results to prove whether or not resistance of wire depends on its length. For this experiment the equipments used are, 1m length of nichrome wire which is a copper alloy, a voltmeter an ammeter, crocodile clips and a battery pack. When the equipment was set up the voltage and current were recorded with different lengths.

Metals are good conductors of electricity. This is because in metals, there are free electrons to move between the positive ions which are arranged in a regular lattice, if a Voltage is applied across a length of a wire this will give the electrons increased energy and push them in the same direction, causing a current to flow. Resistance is caused by electrons colliding with a stationery positive ion. Resistance blocks current and so a greater resistance means a reduced current. A material with high resistance is one in which the positive ions keep restricting the progress of the electrons.

If an electron collides with positive ion the electron will be slowed down and some of its energy picked up by the ion. If this happens often there are two effects, firstly the current will be reduced since less electrons are flowing through the wire, secondly the metal will get hotter as the energy is transferred to the positive ion. Length before length increased after Form previous work it was discovered that the voltage across a wire is directly proportional through it. In other words, if the voltage is increased the current is increased while resistance remains constant, as long as the wire does not get hotter.

However from my investigation we are going to find out if the resistance of the circuit will or not change if the length of one of the wire is increased. My hypothesis is therefore that, if you increase the length of one of the wires you also increase the resistance, because there is more stationery positive ions, therefore restricting the progress of the electrons, because the electrons collide with more of the stationery positive ions, this then slows down the electrons and reduces current. Therefore making resistance to be greater. Analysis.

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Resistance = voltage, V Current, I As you can see on the graph of current against length there is a curve pattern, which show that the longer the length of the wire the less current transferred, and the shorter the length of wire the more current is transferred.

And on the graph of resistance against length the results are scattered in a pattern of positive correlation. I have drawn a line of best fit on the graph. (On the graph of resistance against length of wire) I will numerically prove that resistance is directly proportional to the length of the wire. That is if you double the length of wire you also double the resistance. I will use lengths (wire) of 0. 20 and 0. 40. I predict that the end results of the resistance will be doubled. Test Results Length of wire.

I can therefore say from the result of this investigation that the resistance of an electric wire does depend on its length, and the resistance of the circuit is greater if the length of one of the wire is increased, because there’s are more stationery positive ions and more electrons to collide, and more collision means greater resistance. therefore restricts the progress.

From the graph I can see that resistance slows the current, i.e. the greater the resistance the less the current. Therefore I am positive that my results have supported my prediction as you can see that if you increase (double) the length of a wire you also increase (double) its resistance. Evaluation My experiments were successful in that I achieved my aim; it proved my theory as you can see from my analysis. I think this experiment is fair, because my results fitted a visible pattern on the graph. In the experiment the measurements made were fairly accurate.

Firstly, in the experiment a voltmeter and an ammeter were used the results of both readings was to 2 decimal place But however the reading fluctuates this shows that the figures were fairly accurate. The length of the wire on the other hand could not have been very accurate, being that it was cut by the judgement of an human eye, this could have been improved if a computer machine was used to cut the wire to make it perfectly 100% accurate. My data is reliable, because I have used it to help me work out a formula as you can see in my analysis that L1*R2=R1*L2.

There were also, enough points on the graph to make it reliable because I used 10 different length of wires, this was enough to plot some points on the graph, as you can see that my results fitted a visible pattern and I could also draw a line of best fit and a curve, and also come to a conclusion that increasing the length of a wire you also increase its resistance, but bearing in mind there was one point on the graph of current against length which is indicated with a circle it did not fit the pattern. I have omitted from drawing this point with other results on the graph because it will disfigure the way the graph was meant to be.

This point which did not fit the pattern could have been caused by different possible reasons, it could be that the wire got to hot at a stage, which could have affected the result because increasing the temperature of a metal, causes increase in energy and amplitude of vibration of the metal particle, which will result in more frequent collisions between the electrons and the metal particle hence increase in resistance. Or on the other hand it could be caused by human error that is the reading of the ammeter or voltmeters were fluctuating, and a wrong result could have been taken.

The procedure used in this experiment was suitable, the correct equipments were used, voltmeter, an ammeter, crocodile clips, and a battery pack. The experiment could have been improved if it was to be repeated, the wires could have been cut with different lengths i. e. in smaller gap range 0. 15, 0. 20, 1. 2 and etc. I could have used a different type of wire each time, which means the wire wouldn’t get as hot as it was when it was done with the same wire making the result more accurate, I could also have used a wire with a good metallic conductor for example pure copper.

And I could have also repeated the test 2 or 3 time and at the end sum up and average to make it more accurate. I could have done some further work such as ? Using a different wire, pure copper, this is because it contains more ions It is a transition metal, which makes a good conductor of electricity. Also I could have otherwise completely changed the whole investigation to see the effect of cross sectional area on the resistance, the same length will be cut from reels of constantan and manganine wire which have different diameter.

The results will show that if a is the cross sectional area, R l/a. {The area is , whereby r is the radius, or which is where d is the diameter. } Which I predict will be, the thicker the wire the lower the resistance of a given length. If the diameter is doubled the resistance decrease to one quarter, of its original value for the same length of wire. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section. Download this essay Print Save Not the one? Search for.

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