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In this investigation I will be looking at how the resistance of the wire changes when I change a factor and keep the rest constant.

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Introduction I will be changing the length of the wire and then investigation the change in resistance. Aim In this investigation I will be looking at how the resistance of the wire changes when I change a factor and keep the rest constant. Plan Background Knowledge Resistance, in electricity, property of any object or substance to resist or oppose the flow of an electrical current. The quantity of resistance in an electric circuit determines the amount of current flowing in the circuit for any given voltage applied to the circuit, according to Ohm's law. The unit of resistance is the ohm, the amount of resistance that limits the passage of current to one ampere when a voltage of one volt is applied to it. The standard abbreviation for electric resistance is R and the symbol for ohms in electric circuits is the Greek letter omega, ?. For certain electrical calculations it is convenient to employ the reciprocal of resistance, 1/R, which is termed conductance, G. The unit of conductance is the mho, or ohm spelled backward, and the symbol is an inverted omega, ?. The resistance of an object is determined by the nature of the substance of which it is composed, know as the resistivity, the dimensions of the object, and the temperature. ...read more.


So if the length is doubled the resistance should also be doubled. This is because if the length is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance. My graph should show that the length is proportional to the resistance. Preliminary Study Method (Rough) At first I will set up my experiment. The wire that I will be using will be placed on a ruler, making it easier for me to take the readings of the length. I will attach crocodile clips at the right places and take the readings of the voltage and current. I will take 5 readings (at 10cm, 15cm, 20cm, 25cm, 30cm). After doing the dry run I found out that I made some mistakes. I took all 5 readings from the same wire. This meant that the wire kept getting thinner and thinner because of the heat from the resistance. I knew this because I measure the wire before each test. I have also discovered that conducting the experiment in this way was unfair because each wire had a different thickness. So in my real experiment I will use different wires for each reading. Equipment List Power Pack, Ammeter, Voltmeter, Ruler, Wire, Resistor. ...read more.


The resistance of a wire depends on the number of collisions the electrons have with the atoms of the material, so if there is a larger number of atoms there will be a larger number of collisions, which will increase the resistance of the wire. If a length of a wire contains a certain number of atoms when what length is increased the number of atoms will also increase. Evaluation From my results table and graph I can see that my results that I collected are very reliable. I know this because my results table does not show any individual anomalous because all the averages lie along the same straight line. To improve my results I could have used a digital voltmeter instead of an analogue meter. I would do this because if the needle in the analogue voltmeter is bent then the readings given off will be false whereas a digital voltmeter does not rely on a needle or any other manual movements. In addition, looking back on to my method I can see that I have performed my experiment in a right way. I have used a Rough Method and a Method because I could make any written mistakes in my Rough Method, this way my method has been written well. ...read more.

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