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# The resistance of a wire.

Extracts from this document...

Introduction

Title: The resistance of a wire

Prediction:I predict that the longer the wire the higher the resistance will be, and the shorter the wire the lower the resistance.

Hypothesis

In electricity, resistance is the property of an electric circuit or part of a circuit that transforms electric energy into heat energy in opposing electric current. Resistance involves collisions of the current-carrying charged particles with fixed particles that make up the structure of the conductors. Resistance is often considered as localised in such devices as lamps, heaters, and resistors, in which it predominates, although it is characteristic of every part of a circuit, including connecting wires and electric transmission lines.

Apparatus:

• Voltmeter
• Ammeter
• Crocodile clips
• Power unit
• Wires
• Meter ruler
• Wire just over1 meter

Diagram:

Variables:

Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy. This causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance.

Wire length: If

Middle

According to my research, the resistance of a wire generally increases as the temperature of the wire increases. This means that if the heat of the wire does increase, than the results we be inaccurate and therefore the experiment will have to be repeated. That is why it is essential to keep the wire at a constant.

I am going to measure the voltage using a voltmeter and the amps using an ammeter (A). I will use a meter ruler to measure the wire.

Safety

• Do not turn the Amps over 0.5A because wire will get hot and could burn or scorch the person using it.

Method

1. Set up the equipment as shown in the diagram.  You will need crocodile clips, a meter ruler, a voltmeter, wires, a meter length wire and a power unit.
2. Set wire to specific length (starting with 10cm). Do this by moving the crocodile clips along the ruler with the wire on and set to the correct length. Make the measurement as accurate as possible. To make this as accurate as I could I left 2cm at each end of the wire and measured in the amount I was testing each time.

Conclusion

Evaluation

Having read through the investigation I would have changed a few things about the method used I would have used a way far more accurate than that used to measure the wire, because the wire was not exactly straight and could not be straightened. If I were to do this experiment again I would have to use a straight wire.

I would also have used something far more accurate to replace the power unit as when the power it produced was measured it constantly fluctuated.

From the results I have identified an anomaly which I have highlighted in red to make this experiment more fair I should repeat this result or exclude it from my final set of results. The averages taken from the table of results could be far improved by repeating the results more times i.e. 5 times or more, this would also insure there were no anomalies and make the test much fairer.

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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