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Investigating one of the factors that affects the current in a wire.

Extracts from this document...

Introduction

Investigating one of the factors that affects the current in a wire.

In this investigation I will be examining a factor that affects the current in a wire. It is a free choice to what factors I choose to investigate but it must show how it affects the current in a wire and why.

Scientific Knowledge

As any other material metal (wires) consist of millions of atoms. Every atom is surrounded by a number of outer shells.  Each outer shell will contain a number of electrons in it. Depending on the type of material the number of outer shells and the electrons within it will vary.

Metals conduct electricity because they have free flowing electrons. However different metals will have different number of electrons and therefore the conductivity of the metal will vary.

The current travels within the wire by hitting the electrons. Once one of the electrons is hit it moves and hits another. This causes a chain movement we call this free flowing current. The current is pushed by voltage. The higher the voltage the harder the electrons are pushed and therefore the current travels faster. Suppose the distance the electrons have to travel is longer then the electrons will have a harder time moving jumping from one atom to another over a longer distance i.e. there is more resistance.

 So if we double the length of a wire, the number of atoms in the wire doubles, so the number of jumps double, so twice the amount of energy is required: There are twice as many jumps if the wire is twice as long.

Middle

Pilot Test

I am going to do a pilot test using my lowest and highest results theses are 100mm and 1000mm. The test will show me if my method needs adapting for example whether I will not get a good variation in results so I need to make my highest result higher or my lowest result lower in order to get a better range of results. It also gives me an idea about what results I should be expecting and if I am going the right way around getting them

Pilot Results Table

 1st Reading 2nd Reading Length mm Voltage (v) Current (A) Resistance Voltage Current Resistance Average Resistance 100 1.07 0.22 4.8 1.03 0.20 5.1 4.9 1000 1.25 0.03 41.6 1.27 0.04 31.75 36.6

As you can see I have got a good range of results on my table. It tells me that my prediction is basically correct because the longer wire compared to the shorter wire has a larger resistance and less current.

I am not going to change anything in the main experiment because I believe that I will get a good range of results and will prove my prediction.

Recording Results

Conclusion

Make sure the ammeter is set to 0 when there is 0Amps. Also make sure ammeter can read low values accuratelyThe length of the wire that is relevant is between the crocodile clips because any wire outside the crocodile clips has no current and therefore irrelevant to this experimentMake sure the voltmeter is set to 0 when there is 0volts. Also make sure Voltmeter can read values accurately.Make sure the crocodile clips are powerful and make a good electrical contact with the wire

This also proves that George Ohms law is correct. He defies resistance as:

Resistance property of any object or substance of resisting or opposing 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.

I could expand this experiment by having different cross sections of wire and I could run the experiment at different temperatures. Also I could see how different materials resistance varies. Because metals all have different properties.

II could also find out how much energy is transferred by each coulomb of charge by doing

Power (Watts)  = Current x Voltage (volts)

Or how much electrical charge there is measured in coulombs. One coulomb is the amount of charge passing through a particular point in a circuit each second when the current is one ampere. I could find this out by doing

Charge (coulombs) = current (amperes) x Time (seconds)

I Conclude that the longer the length of wire the higher the resistance will be.

.

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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