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Investigating how the resistance of a wire is affected by its length.

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What are the factors that affect the resistance of a wire choose one and investigate it.

To choose a factor, which affects the resistance of a wire I will first have to choose a factor for the following: Temperature



Resistance is the amount of energy lost from the voltage flowing across a conductor. Resistance is measured in the unit ohms. This means that a resistance of a conductor requiring the potential difference of 1 volt across its ends to produce a current of 1 ampere. For a given metal conductor at a constant temperature the value is the same whatever the current this is Ohm's law.It’s named after the German physicist, George Simon Ohm (1787-1854). This law is expressed in the form I = V/R; R is the resistance of the conductor. Any conductor possessing resistance gives off thermal energy when a current flows through it. Joule’s law describes this effect.

  I have chosen length for my investigation; length will be my independent variable, (the length will be measured in centimetres).

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The lengths I have chosen for the experiment are 60cm, 50cm, 40cm, 30cm, 20cm and 10 cm

hope will gave me give me good results as the values are more spread out which should give a better set of results. For the volts in the circuit (controlled by the variable resistor)


However for every experiment there must be safety precautions .So therefore the power supply should not exceed 2volts as if the voltage is any higher the wire will heat up which in turn if touched would burn the skin. Also with an increase in voltage you will get an increase it temperature which will effect the resistance of the wire and thus further decrease the accuracy of the experiment. It is also very important not to connect the ammeter in parallel with the power supply as this would burn out the ammeter.

 With all this considered I should get accurate results. With these results I should be able to plot a scatter graph, with resistance on the Y axis and length on the X axis.

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From the graph I have drawn it can be seen that there is a very clear trend; as the length of the wire increases so does the resistance and that it the increase is constant. A line drawn in a straight line on the graph, which goes through the origin, indicates this.

To Conclude I think that from my table of results I can accurately say that my prediction was precise. As The length of wire increases the resistance increases. This happen as when the length of the wire is increased the electrons that make up the current have to in turn  travel through more of the fixed particles in the wire causing more collisions and therefore a higher resistance.

I feel that overall my results were support my theory that as the length of wire increase’s so does the resistance of the wire.

 In my opinion the only way to make the experiment more accurate, would be to use a different method for example we could use another rheostat in place of the wire, as a rhestat is fundamentally just a coiled wire that is connected at different lengths to change the resistance of the circuit.

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This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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