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Resistance in a Wire.

Extracts from this document...

Introduction

George Mitchell School (13410)

Science Coursework.

Resistance in a Wire

Aim

The aim of this experiment is to find out if or how different lengths affect the resistance of a wire by carrying out an investigation.

Scientific Information

Resistance is a force, which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long.

Resistance is measured in ohms. A resistor has the resistance of one ohm if a voltage of one volt is required to push a current of one amp through it. Resistance is dependent on several factors, heat, cross sectional area, substance and length. Length is the variable that I have chosen to investigate. The resistance of a wire increases as the length increases.

George Ohm discovered that the emf of a circuit is directly proportional to the current flowing through the circuit. This means that if you triple one, you triple the other He also discovered that a circuit sometimes resisted the flow of electricity. He called this resistance. He then came up with a rule for working out the resistance of a circuit:

V/I = R

V - Volts
I - Current

Middle

Equipment

The equipments I will be using for the experiment are:

• Power supply
• 1 Ammeter
• 1 Voltmeter
• 1 Metre ruler
• 2 crocodile clips
• Copper wire of up to 500 mm in length.

Method

I have chosen to use Copper wire because from my own knowledge I know that this type of material and thickness will have the most resistance and therefore it will be easier to measure and differences in resistance. To ensure a fair test whilst carrying out my experiments I am going to be very careful when selecting my independent variables which are the width of the wire and the wire material. I am going to use a constant voltage of 2 volts and the same width and same material, which is Copper.

• Meter ruler: To measure the wire being tested.
• Copper wires: Same width of wire and same material but testing different lengths.
• Crocodile clips: To connect the wire to the rest of the circuit.
• Voltmeter & Ammeter: To measure the resistance.
• Wires: connect the above items and to make a circuit.

In my experiment I have chosen to use an ammeter and voltmeter, I have done this so that I can work out the resistances from the volts and amps. I shall calculate the resistance of the wire using the equation below.

RESISTANCE = VOLTS / AMPS

To do the experiment:

Conclusion

I don’t think there were really any anomalous results as on my graph; the line is straight with it running through most of the points. I have compared my results with another member of my class, who done the same experiment and I also looked upon the results of same experiment on the internet, the results were very similar to mine showing that they are reliable. My results are also reliable because my results table does not show any individual anomalous results this means that I did not have to leave any results out of my averages because they were anomalous. Also on the graph I can see that none of the averages plotted are anomalous because all the averages lie along the same straight line. If I was to carry out the investigation again I can think of some improvements that I could make to get better results, I would have to make sure the wire was the exact right length and also it was not bent because it could make the readings different. Also it would be purposeful to give time to wire to cool down after taking each reading.

If I had more Time I would of liked to of tried more lengths and material of wire or try out some of the other variables (voltage, current etc.).

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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