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

Factors affecting resistance (R) of a wire

Extracts from this document...

Introduction

Factors affecting resistance (R) of a wire

Introduction                                                                                                        Resistance is the 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 unit of resistance is the ohm and the symbol for ohms in electric circuits is the Greek letter omega, Ω. 1 ohm is the amount of resistance that limits the passage of current to one ampere when a voltage of one volt is applied to it.

Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.

The basic law of current flow is ohm’s law. Ohm’s law was named after its discoverer George Ohm (1787-1854) a German physicist who researched electrical current in circuits.  George Ohm discovered that the amount of current flowing through a circuit is directly proportional to the electromotive force (volts) impressed on the circuit. Also it is inversely proportional to the total resistance of the circuit. George Ohm also discovered that the circuit also resists the flow of electricity.

George Ohm discovered a rule for working out the voltage of a circuit:

V = I R

V = volts

I = current

R = resistance

This formula can be rearranged to find the current or resistance by dividing the voltage by the known factor.

...read more.

Middle

Make sure the mains to the power supply is switched off when removing the wire from the circuit to be measured.

Fair test

In order for this experiment be fair, I must take repeats. I will read the ammeter and voltmeter carefully. The room temperature must also be kept constant.  I will use the same ammeter, voltmeter, and power pack, throughout the experiment. To get accurate results I will use a digital ammeter and voltmeter. The voltage going through the circuit will be kept the same every time. Also, the same wire will be used every time so that the material of the wire remains the same.

In this experiment two factors will be changed – the length and thickness of the wire. I will perform an investigation on each variable one at a time, so I don’t get mixed up with the variables. All other factors will be kept the same. These precautions will make my final results more reliable and keep anomalies at a minimum to make the entire investigation more successful.

Apparatus

The following apparatus will be used in the experiment.

  • Power supply
  • 7 Wires
  • Ammeter
  • Voltmeter
  • Wire cutter
  • Variable resistor
  • 2 crocodile clips

Method

First, the power pack was set up with wires leading out of it. The power pack was set as 4v and was at a direct current supply. The wire was connected to an ammeter and then to a resistor by crocodile clips.

...read more.

Conclusion

Most errors in our experiment were encountered in the measuring of the wire. This is because it simply was not very practical to hold a piece of wire straight, whilst holding it next to a ruler and then trying to accurately fix crocodile clips to the right part on the wire. Also I do not feel that the crocodile clips were always fixed securely to the wire with a good connection. This also meant that they were easy to move about on the wire changing the length of it. Errors rarely occurred in the setting of the current and the reading of the voltage. Another example of this is the wire was never totally straight when we started the experiment, which may also affect the resistance of it

I do not think that doing any more results in our experiment would have made it any more accurate. I feel that the only way to make it more accurate would be to use a different method – perhaps were we had a bar that did not bend in place of the wire. We could even use a rheostat in place of the wire, because it is essentially a long coiled wire that is connected at different lengths to change the resistance of the circuit.

The results would then have been more reliable and would definitely produce better results, however the results in this experiment are fairly reliable and they did support my prediction. So all in all I think this was a good experiment and best that could have been done with the time and resources available.

...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)

    x A [] 0.12 5.49 4.8 0.25 2.86 3 0.39 1.62 1.8 0.65 0.97 0.9 This graph shows that the cross sectional area of the wire is inversely proportional to the resistance of the wire. GRAPH III: * A series circuit as a factor affecting the resistance of a wire:

  2. Physics GCSE Coursework:Factors affecting the resistance of a wire

    of using an ohmmeter I have chosen to use an ammeter and voltmeter, from which I will record all my results. This is what to do once you have connected all the components of the circuit in the above fashion and connected all the wires to the mains power supply in order to create a flowing circuit.

  1. Discover the factors affecting resistance in a conductor.

    All wires must be checked for breaks or any bare wire that may show, otherwise this could result in electrocution of the user. The method will be performed taking into account all of the laboratory safety precautions in order to perform a safe investigation.

  2. Factors Affecting the Efficiency of a Wind Turbine

    The same arrangement was used except that this time a hair dryer didn't move. The most efficient blades were used again this time. In short everything was constant except for temperature. TABLE OF RESULTS Number Of Complete oscillations Number of Grids used by oscillations How temperature of air affect efficiency of a windturbine.

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

    I must also keep the surrounding room temperature the same or the particles in the wire will move faster (if the temperature is increased) and this will therefore have an effect on the resistance. To keep the cross-sectional area of the wire constant, I will note down the SWG of the wire I'm using.

  2. Investigating the factors affecting the resistance in a wire

    of amperes (A), V is the potential difference measured across the conductor in units of volts (V) and R is the resistance of the conductor in units of ohms (?). In circuits, three equivalent expressions of Ohm's Law can be used interchangeably: The interchangeability of the equation may be represented be a triangle (see Figure 4), where V (voltage)

  1. Factors Affecting the Current Flowing

    It is only the electrons which are free to move, these travel towards the positive potential. The electrons are accelerated towards the positive potential and their kinetic energy increases. But as they move through the metal they collide with the metal ions, this has the effect of slowing the electrons

  2. Free essay

    Factors Affecting the Resistance of Wire.

    result in more unreliable results and because of it being more difficult to measure it would take longer to carry out the investigation meaning I could not repeat it a sufficient number of times to get more reliable results. If I chose to change the cross-sectional area it would also

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