• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

To investigate resistance in a wire when its length is varied.

Extracts from this document...


Investigation into electrical resistance of a metal wire

Aim- To investigate resistance in a wire when its length is varied

Preliminary information-

In a metal the electrons are free to move around in what is sometimes called “a sea of electrons.” All materials resist the flow of electricity through them. This is because when electrons move through a conductor such as a metal they collide with the atomic lattice of the conductor material because the protons are also moving slightly due to their thermal energy.

When an electron collides with the protons in the atomic lattice it will lose some of the kinetic energy of its motion along the conductor. This energy loss is the cause of electrical resistance.

The more resistivity a material has, the more insulating its effect is and if a material has little resistivity it is a good conductor.  Resistance is defined by the following equation:         

resistance R=        potential difference V

                                current I

This is Ohm’s law. It means that the amount of steady current through a resistor is directly proportional to the potential difference across the resistor. Therefore if the voltage between two ends of a wire quadruples the current going through the wire will quadruple and the ratio V to I will stay the same.  Ohm’s law does not work for every material but for most of them.

The unit of resistance must therefore be the volt per ampere but this is given the name ohm, which is represented by the Greek letter omega: Ω.

...read more.


I will keep all these factors the same except length, which I am investigating, in order to keep it a fair test. I will also use the same equipment throughout the experiment including the same piece of wire.    

Apparatus        -A piece of constantan (resistivity at 25˚C=49 x 10   Ω/m) wire 1.1m                     long to use to measure resistance at different lengths. I will cut it at 1.1m and wind it round the safety pins so that it is kept firmly in the desk

-A metre rule to measure how far down the wire to clip the crocodile clips for each reading

                -Two drawing pins to keep the wire fastened to the desk

                -A multimeter set to ohmmeter setting to measure the resistance

                -Two leads to attach the multimeter to the constantan wire

                -Two crocodile clips to attach the leads to the wire

                -Wire cutters to cut the wire at the beginning of the experiment

Prediction-        I predict that as the length of my wire increases so will my resistance and it will do this in proportion to the length. I predict that my resistance at 1m will be double that at 0.5m because there will be double the amount of atoms for the electrons to collide with so there should be twice the number of collisions. I also predict that my resistance at 0.9m will be three times my resistance at 0.3m. I know this because R ∝  l.

...read more.


I have a lot of confidence in my results because I have repeated my experiment a few times and every time I have repeated it I have come up with the same results. To make my experiment even more reliable I could repeat it again but I think that to repeat it three times is sufficient.

To further this experiment I could investigate longer lengths of wire or shorter lengths of wire. I would carry out the experiment very similarly to how I carried out this one. I would collect a range of values from 1.1m to 2.0m in 10cm intervals. I would keep other things constant as in original experiment. I would carry out the method as following:

-Set up electrical circuit as shown in diagram including cutting the piece of constantan wire to different lengths with wire cutters

-Record resistance for different lengths of wire, clipping different wires in between the two crocodile clips  

-Repeat experiment three times to improve reliability in case some results were incorrect and take an average

  I could also investigate length using different materials such as                 . I would use the method I used in the original experiment to do this and I would just change the material to        .  

Bibliography        - Key Science Physics by Jim Breithaupt

  • www.physics.gla.ac.uk

- University of Bath science: Physics by Robert Hutchings

Imogen Hagarty                

...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. How does length and width affect resistance

    This transfer on collision is what causes resistance. So, if we double the length of a wire, the number of atoms in the wire doubles. This increases the number of collisions and energy transferred twice, so twice the amount of energy is required.

  2. Design an experiment to predict and test the output from a simple AC generator.

    1.20E-04 0.17 5 3.42 188.10 1 1.60E-03 0.36 5 3.42 188.10 2 9.00E-04 0.25 5 3.42 188.10 3 7.10E-04 0.22 5 3.42 188.10 4 5.60E-04 0.21 5 3.42 188.10 5 4.50E-04 0.20 5 3.42 188.10 6 4.00E-04 0.19 5 3.42 188.10 7 2.80E-04 0.18 5 3.42 188.10 8 2.00E-04 0.18

  1. Determine how the effect of electrical resistance changes with varied length of a metal ...

    Electric charge is not created or destroyed. It is a property of matter. We don't usually observe the charge because equal numbers of positive and negative charges cancel out one another. In a series circuit, the current remains constant throughout the circuit, because no charge is lost.

  2. To investigate the effect the length of a wire has on the resistance

    How resistance is measured? Resistance is measured in units called ohms. A resistance of one ohm carries a current of one ampere if there is a potential difference of one volt across it. Resistance can be worked out by the equation below.

  1. Investigation is to find out how the resistance of a wire is affected when ...

    * Voltmeter Safety Precautions - We plan to carry out this practical safely by making sure we handle the equipment carefully and we are sensible. Also, logical safety procedures for using electricity such as plugging the wires correctly and not have wet hands when switching the socket on.

  2. Find out (through an experiment) how much resistance a piece of copper wire will ...

    This is because at higher temperatures, the particles of the conductor are moving around more quickly, thus increasing the likelihood of collisions with the free electrons. Variables Input: * Length of wire. * * Material of wire. * Width of wire.

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

    Thirdly, the material used would be a factor. If the material being used contains atoms with a large number of electrons on the outer shells, then this means there are more electrons available. So, in theory, if the material has a large number of atoms, there should be less resistance,

  2. In our experiment we aimed to investigate the effect of the length of wire ...

    (Current (A) then we took the average the two resistances, then recorded our results in a graph. The Circuit This shows the copper wire, voltmeter (volts), ammeter (current), power pack (5V) and connecting wires. Resistance The resistance is calculated using the current flowing in the circuit, and the voltage of the circuit.

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