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In this coursework, I will be analyzing and proving that although metallic conductors are good conductors of electricity, they are affected by resistance.

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Introduction

PLANNING

In this coursework, I will be analyzing and proving that although metallic conductors are good conductors of electricity, they are affected by resistance. But there are factors affecting the resistance of a conductor, and through my experiments I am going to prove that.

CONDUCTORS

We know that there are two types of conductors of electricity. Good conductors and bad conductors. Good conductors are that which conduct electricity the best. There are also some conductors, called semi-conductors, since they only half conduct the electricity that is passed through them. However, there are some materials, which resist the flow of electrons more that others do. These bad conductors are called insulators. Insulators are not needed to prove the factors affecting resistance, since they will be very invaluable, as they do not conduct electricity in the first place.

When we talked about conductors conducting electricity, the very first question that comes up into our head is,

‘How do conductors conduct is electricity?’ In order to understand this, we have to learn about the structure of a metal, and to go deeper into it. Every piece of metal is made of electrons in the shells around the nucleus, which contains the protons and neutrons. Thus the atom is stable when it has the same number of electrons and protons. But when we examine a piece of metal closely, we can see that they give out free electrons, to form a sea of electrons, and it is these electrons, that can carry the charges, thus conducting electricity.

Middle

In my experiment, I will use a varying current, in order to find if the resistance is a constant, and if my predictions are predicted right. If I use a high range of voltage values, then  the electrons move with a greater force, and so the collisions will be more impactful, and so, more energy will be lost in these collisions, and so, the wire will heat up more. As a result, the resistance value will be higher, as resistance increases, with temperature. Nevertheless, if my voltage value is too low, then the readings will be so low, that it will not be able to be picked up by the ammeter. In addition, the voltage to be selected differs, from conductor to conductor. For example, if I choose copper as my conductor wire to be tested, then I will have to choose a lower range of voltage values, in order that the rapid heating of the wire is prevented, which could result in the wire snapping. But if the metal to be chosen has a lower conducting power, then it is possible to choose a little higher range of voltage values. I have chosen to use NICHROME, as it is very suitable, since it has moderate resistance. At the same time, I will choose a current within the range of 0.0 - 2.0, as it shows a reasonable change in the current value, without causing much heating.

EXPERIMENTAL PROCEDURES

In order to record my observations, I

Conclusion

The resistance for the 0.4 mm + 0.4 mm wire is shown by :

The resistance for the 0.56 mm wire is shown by :

I did a prior test, or an introductory pre – experiment test, to get me used to how to know to work the rheostat, and connect the circuit, and the results I got, are on the next page.

Analyzing evidence

As you can see from my graphs, which are more or less like the graphs, I had expected to get, in my planning,

In order to show that when the length of the wire was changed, the resistance changed proportionately, I created this bar graph. Thus as you can see, when the lengths in crease, the resistance of the wire increases, as there are more collisions between the electron, (which is moving from the negative end to the positive), and between the atom. When length is doubled, resistance doubles. Therefore length is directly proportional to resistance.

In addition, I compared the resistance obtained from the tables, when I changed the thickness of the wire, and this is the resulting pie chart. Here too, it is plain to see that when the thickness doubles, the resistance is halved. This is due to, when the thickness increases, there is more space for the electron to pass through, without colliding, and thus resistance decreases. Thus resistance is inversely proportional to resistance.

Where as in my series and parallel graphs, the gradient achieved for both the graphs is almost the same, thus I state that the resistance of a longer wire, is the same as two shorter wires connected together in a series circuit. In addition, the resistance of a thicker wire is the same as that of two thinner wires connected in a parallel.

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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3 star(s)

This is a well detailed report that has a good structure.
1. There is a running commentary that needs to be removed from this report.
2. The primary data is missing.
3. There is no need to include examples of the tables and graphs before they are being included.
4. There is no evaluation.
***

Marked by teacher Luke Smithen 05/09/2013

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