• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14

To investigate the factors which effect the resistance of a metal wire.

Extracts from this document...

Introduction

Hannah Clapham                                                                   Physics Coursework 2003

To investigate the factors which effect the resistance of a metal wire

Aim: To find how different factors affect the resistance of a metal wire.

Hypothesis: For this investigation I think that the thinner the wire the higher the resistance of the wire.  This is because the electrons in the wire can flow more easily when the wire is thicker because there are less collisions and therefore less resistance so when the wire is therefore thinner there are more collisions and the electrons flow more slowly creating more resistance.

Knowledge that I already have is Ohms law and how to measure resistance using a voltmeter and an ammeter. Ohm's law states that the amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive force impressed on the circuit and inversely proportional to the total resistance of the circuit. The law is usually expressed by the formula I = E/R, where I is the current in amperes, E is the electromotive force in volts, and R is the resistance in ohms. This enables us to work out

the resistance using the current and voltage.
R=V/I.

Theory:Atoms are made up of a positively charged nucleus surrounded by negatively charged electrons. In solids, one or two of the electrons in each atom are used to form the bonds between atoms that hold the solid together. In a metal these bonding electrons are free to move through the entire solid. These are often referred to as “free electrons”. An electric current is a flow of charged particles and when a voltage is applied to a metal, the free electrons can flow through the metal.

...read more.

Middle

The tick marks along the barrel of the micrometer represent halves of millimetres. Every revolution of the knob will expose another tick mark on the barrel, and the jaws will open another half millimetre. There are 50 tick marks wrapped around the moving barrel of the micrometer. Each of these tick marks represents 1/100 millimetre.

To read the distance between the jaws of the micrometer, simply add the number of half-millimetres to the number of hundredths of millimetres. For example the above diameter is 2.62mm (2.50+0.12mm)

Method for measuring the diameter of the wire:

  1. Put the wire you want to measure between the jaws of the micrometer.
  2. Use the ratchet knob to close the jaws on the wire until it clicks. When it clicks it is sufficiently closed.
  3. Look at the fixed barrel and the moving barrel and record the two numbers. Now add these two numbers together and this is the diameter of the wire.
  4. Take away the zero error of the micrometer. To work out the zero error you close the jaws using the ratchet knob until it clicks. You then read off the measurement as though you would for a wire.
  5. Repeat the reading a further 2 times to improve accuracy by taking an average of the 3 readings.

Fair Test: To make sure it is a fair test I will use the same length of wire each time. I will also make sure that I use the same multimeter throughout my experiment to avoid any inaccuracy in changing equipment. The only thing that will change is the diameters of the wire.

The Data: I am going to collect data on the different resistances of varying diameters of wire. I will increase the diameter of the wire each time by 2 SWG, so the diameter will range from 18 SWG to 38 SWG.

...read more.

Conclusion

Evaluation:  The results I obtained from this experiment were initially not quite as clear as I had hoped, but after  changing my method for the thicker wires this caused the results to become a lot more accurate.  The accuracy of my results was very good as when using the variable resistor methid the results were taken  up to 3 decimal places and then measuring the diameter the micrometer reads to 100th of a millimetre. Although some of my data was not 100% accurate the  graphs did not show these results to be anomalous as they fitted almost perfectly to the best fit line. By taking each of the readings 3 times  I increased my accuracy as this meant I coul d take an average of my results and would decrease any anomalous results.

My experiment went well although there are a couple of areas which could be improved if I were to do this experiment again. The first of theses is  the straightening if the wire. When straightening out a 1 metre length of wire I found it very difficult to get the thicker wires straight which could have lead to some inaccuracy. To improve this I could use the follwing method. Clamp one end of the wire and  place a weight on the other other to stretch out the wire hopefully straightening out any bends and kinks in the wire. Although doing this would straighten the wire the wire may also stretch. I would therefore take the diameter reading after straightening the wire as if the wire had stretched with the weight the diameter may have decreased.

I would repeat this investigation I would investigate more factors such as heat and length so that I could see how these affect the wires resistance. I would also carry out this investigation further and compare the properties of other conductive metals so I could see how each factor affects metals with varying resistivity’s.  

Page  of

...read more.

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

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Electricity and Magnetism essays

  1. Marked by a teacher

    To investigate how the resistance, R, of a length of wire, l, changes with ...

    4 star(s)

    is approximately 1 x 1029. The diagram below shows a part of a wire of cross-sectional area A. the current in the wire I. There are n free electrons per metre3 of the wire and the charge on an electron is e (1.6 x 10 -19C)

  2. An experiment to find the resistivity of nichrome

    Although it would be easy to obtain and record the data the graphs that I would be able to draw up would not be interesting. For the temperature of the wire I would not be able to carry out a fair test because it is extremely difficult to produce and control the range of temperatures needed without the correct equipment.

  1. Free essay

    Resistance in a wire

    This made me question why the resistance was higher in the longer wire if the shorter wire produced more energy. However I realised that the longer lengthened wire possessed the higher resistance therefore the product of the light energy effects the results.

  2. An Experiment To Find the Resistivity of a Wire

    I will find the Resistance of this particular length of wire, which is the gradient of the straight-line graph. I will repeat the experiment with the following length of wire connected firmly between the crocodile clips: 0.10m, 0.15m, 0.20m, 0.25m, 0.30m and record my result in a table.

  1. Resistance of a Wire Investigation

    As these results had a range of only 7 readings, from 0.1 mom, and were only repeated twice, and that the results are not 100% accurate, due to the errors discussed earlier. I would say that these results are not strong enough to base a firm conclusion on because there

  2. An in Investigation into the Resistance of a Wire.

    Step 1 Cut 110cm of the wires E26 (more than 100cm because extra wire is needed to clip the crocodile clips too). When doing this use two rulers side by side start from measuring at the 10cm mark all the time.

  1. The resistance of wire.

    A table was drawn out and the results were recorded. To improve the accuracy, compared to my preliminary results for my main wwdd ddw esdddds aydd ddba ndd kcdd dduk; Experiment, I have decided to set up the circuit with the metre rule selotaped to the bench.

  2. To investigate the factors affecting current in a wire.

    Because the difference between each 1 is not the same (which I had worked out earlier). Length This best fit curve on this graph in exponential. This graph agrees with my prediction. Because if you double the length, the current halves.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work