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

An investigation into factors affecting the resistance Of a metal wire.

Extracts from this document...

Introduction

 An investigation into factors affecting the resistance

Of a metal wire

What is resistance?

Electricity is conducted through a conductor, in this case wire, and travels through free electrons. The number of free electrons depends on the material being used and the size of it. The more free electrons the better the conductor, i.e. it has less resistance. For example, gold has more free electrons than iron and, as a result, it is a better conductor. The free electrons are given energy and as a result move and collide with neighbouring free electrons. This happens across the length of the wire and thus electricity is conducted. Resistance is the result of energy loss as heat. It involves collisions between the fixed particles of the metal, free electrons and impurities. These collisions convert some of the energy that the free electrons are carrying into heat.

How is it measured?

We measure resistance in units called ohms (Ω).The resistance of a length of wire is calculated by measuring the current in the circuit and the voltage across the wire using mille ammeters and volt meters. The current must flow through the volt metre and mille ammeter. These measurements are then used in this formula:

 V = I / R                     where V = Voltage, I = Current and R = Resistance.

This can be arranged to   R = V / I

...read more.

Middle

Prediction

The longer the wire, the higher the resistance. This is because the longer the wire, the more times the free electrons will collide with other free electrons, the particles making up the metal, and any impurities in the metal. Therefore, more energy is going to be lost in these collisions (as heat).

Preliminary experiments

Before the real experiment I carried out some preliminary tests to check a few things. I checked how much power would be needed to keep the ammeter below 2 amps. I then did some tests involving the wire I would be testing. I found that if I use thick wire with a high voltage, the wire gets very hot and this would affect the resistance. So I then decided to use a thinner wire with a low voltage. The current was so low I decided to use a mille ammeter as it is more accurate. I had to make sure the current didn’t go above 200 mA at all lengths. If it did it would mean the current is too high.

  I fastened the wire to the meter ruler at three different points. I noticed that when I attached the crocodile clips the wire began to coil up. This would mean that the length I would be testing is inaccurate.

Proposed method

(Diagram on the page after this)

...read more.

Conclusion

The line of best fit clearly shows that the results followed the expected pattern very well. The points are very close if not touching the line. This shows how the results were directly proportional through out, as the gradient remained the same.

Evaluation

My experiment may have been slightly inaccurate, as there are a few minor details that I did not check. These include that the wire may not have been the exact length as it is very hard to get it exactly the right length just by looking at it. I could have used a more accurate measure and got it exact every time. Also the metre stick was old and may not have been accurate. Over night 2 of my wires had been taken so I had to replace them and start over. If I hadn’t the wires could have different resistances. All these potential problems could have very slightly affected the results but as it was so insignificant it didn’t matter too much.  The resistance of the crocodile clips and wires linking everything together would affect the results as their resistance would have added to the resistance of the nichrome wire.  think my experiment went very well as I did not have to repeat any lengths. At first I didn’t know how to set up the circuit but after I figured it out it was fairly easy.

...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

    The factors affecting the resistance of a metalic conductor.

    4 star(s)

    As their motion becomes more erratic they are more likely to get in the way and disrupt the flow of the electrons. As a result, the higher the temperature, the higher the resistance and we can say that Ohm's law holds true unless temperature changes.

  2. Factors Affecting the Efficiency of a Wind Turbine

    Blades constructed were put on a wind turbine. Plastic ones, which came with the motor, were replaced and never used again. A protractor was placed at the top and the angle was adjusted as shown in the diagram below. A diagram on the left shows a blade being turned with a protractor on top while on the right the protractor hasn't been shown.

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

    I have also found out from my second graph of length against resistance, that increasing the length increases the resistance of the wire. Identification of Trends My first graph of length against current is a curve and it is non-linear.

  2. Resistance of a Wire Investigation

    The rule existed but there was often quite a large margin of error. When measuring light intensity in terms of distance, the greater the distance, the slower the rate of photosynthesis. While the rate of photosynthesis was decreasing, the rate at which it was decreasing at was also decelerating.

  1. Investigate one or more factors affecting the resistance of metal wires

    While doing preliminary work, I have decided that the two factors that I will investigate are the length of the wire and the cross-sectional area of the wire. This means that I must keep the material from which the

  2. Discover the factors affecting resistance in a conductor.

    Outline of procedure The diameter and temperature will be set to a fixed value. The length will then be changed through several different values and the values of current and voltage will be taken to work out the resistance. The diameter will then be changed, and the experiment repeated.

  1. Factors affecting Resistance of a wire

    We will not leave the power pack on for a long period of time as this may lead to a rise in temperature which will make the resistance rise un-proportional to the length as we predicted. This experiment requires safety considerations.

  2. An investigation of the factors affecting the output of a transformer.

    The graph should look like this: Voltage in Primary coil Voltage in secondary coil. A graph to show the theoretical relationship between voltage in the primary and secondary coils. Method Apparatus 1. A power supply that allows the output voltage to be varied. 2. An iron core 3. Wires. 4.

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