• 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

An Investigation into the Effect of the Length of a Wire on its Resistance.

Extracts from this document...

Introduction

Physics Coursework                                                                                    Alice Parker

An Investigation into the Effect of the Length of a Wire on its Resistance

Introduction

        Even the best conductors of electricity slow down the flow of electricity a little. The amount of slowing that occurs as electrons pass through an object is the amount of electrical resistance. The greater the resistance, the lower the current that is able to pass through the wire. For a given voltage, material with high resistivity will inhibit the flow of electrons (or current) through it. Resistivity is the power of resistance. A dictionary defines resistivity as:

  1. The power or property of resistance
  2. Also called specific resistance. Elect. the resistance between opposite faces of a one-centimetre cube of a given material; ratio of electric intensity to cross-sectional area; reciprocal of  conductivity.

Many variables can affect the resistance of a wire. These include

  • Thickness – a thick wire will allow more current through and so it has a lower resistance.                                                                                  
  • Temperature – heat increases the kinetic energy of particles in the wire meaning the particles inside collide more resulting in a higher resistance.
  • Length – As the wire length increases, the current has further to travel and so the resistance increases. This is due to the number of particles in the wire which the electrons collide with.
  • Type of wire – Different types of wire have different resistances. This is their resistivity.

Resistance is measured in Ohms and can be found using Ohm’s Law. In Ohm’s Law, the potential difference measured in volts is divided by the current, measured in amps, to find the resistance, measured in Ohms . Therefore R=V

                      I

...read more.

Middle

image13.png    Using the thin nichrome wire      

image14.png     Using the thick nichrome wire

As it shows a greater variety of results, I have chosen to use the thin nichrome wire in this experiment.          

Method

I will take 80 centimetres of thin nichrome wire and set this up in the circuit shown in the pilot test with the crocodile clip as close as possible to the end of the wire. I will then measure using a ruler 10 centimetres from the edge of the crocodile clip and connect this point to the circuit in order to complete it. Next, readings will be taken from the voltmeter and ammeter in my circuit. I will take readings from the digital displays on both pieces of equipment every 10 centimetres up to 80 centimetres, as this will provide a wide range of results. The experiment will be repeated twice until I have a total of three ammeter and three voltmeter readings from 10 centimetres to 80 centimetres at 10 centimetre intervals, in order to ensure that my results are accurate. I will switch the power pack off between readings to keep the temperature lower as the temperature in the circuit will also affect the resistance.      

        Using these readings, I will calculate the resistance at each length along the wire. To do this, I shall divide the potential difference recorded at every stage by the corresponding current to find three resistances (measured in ohms) at each length. I will then determine the average resistance for each of the 8 lengths measured by adding the three resistance totals together and dividing the sum by 3.

...read more.

Conclusion

        To record the results of this experiment, I would again read the potential difference and current from a voltmeter and ammeter and using the formula R = V     calculate the resistance. Again, I would repeat

                      I

The experiment 3 times with each diameter and record an average.

Another possible experiment would be to change the wire material. This would mean that the wire diameter and length would need to be very accurately checked in order to create a fair test. This would give us information about the resistivity of different metals and would be an interesting experiment to carry out. I would try different metals such as copper, Iron and lead and use the formula R = V  to calculate the

                                                      I

resistance. I would then rearrange the formula

and insert the resistance recorded to calculate the resistivity of each metal.

        The wire temperature could also be adjusted, with the same length and diameter of wire used. This could be achieved with resistors varying in strength. It would be difficult to keep the wire at a constant higher temperature, however. In this experiment, as heat increases the kinetic energy of particles in the wire and therefore speeds up the movement of the electrons within the wire, I would expect the resistance to be higher at higher temperatures due to an increased number of collisions.

Bibliography

Physics for you – Keith Johnson

Physics ‘A’ level revision – Stephen Pople

Complete Physics – Stephen Pople

Letts A level Physics study guide – Jim Breithaupt and Ken Dunn

...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)

    Using a micrometer screw gauge. To ensure that I am conducting a fair test, I have decided to take a number of measures to ensure that this occurs. I am going to use a meter ruler to measure the Constantan wire and ensure that it is the correct length.

  2. Investigating how the resistance of Nichrome wire depends on its length

    I also get the feeling that as length increases; the variation in results also increases. This may be due to the fact that as the wire is longer, then electrons have different possibilities of successfully colliding rather than in a short wire where the length is not so great, and

  1. An experiment to find the resistivity of nichrome

    I am going to use a constant voltage of 2 volts and a constant length of 50 cm. Apparatus: Meter ruler �V To measure the wire being tested to ensure a fair test. Selection of wires �V Different materials and widths but the same length.

  2. Resistance of a Wire Investigation

    individual anomalous results this means that I did not have to leave any results out of my averages because they were anomalous. In addition, on the graph I can see that none of the averages plotted are anomalous because all the averages lie along the same straight line.

  1. How does length and width affect resistance

    y/x=gradient of line 7.45/50=0.149 The gradient of the line above is 0.15(2d.p) The length of the wire affects the resistance of the wire because the number of atoms in the wire increases or decreases as the length of the wire increases or decreases in proportion.

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

    In other words the atoms in a metal exist as ions surrounded by an electrons in this cloud. If a potential difference is applied to the metal, the electrons in this cloud are able to move. So they start to collide with the metal ions in the wire which will cause resistance.

  1. Factors affecting Resistance of a wire

    1.79 1.8 1.8 1.8 1.80 0.994444444 [Hand drawn graph here] Table & Graph for 26 SWG Length (cm) 26 SWG volts 26 SWG amps Average Resistance (?) Test 1 2 3 Average Test 1 2 3 Average Measured in seconds Measured in seconds 10 0.35 0.28 0.30 0.31 0.4 0.4

  2. Resistance of a wire - a number of experiments were carried out to determine ...

    The valence electrons are free to travel through the structure and are no longer situated in the outer shell of any one atom and are consequently called delocalised electrons, frequently identified as the 'sea of electrons' The elimination of the electrons leaves layers of cations behind.

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