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

Investigate if the length and cross-sectional area affects resistance through a circuit.

Extracts from this document...

Introduction

PLAN FOR SCIENCE INVESTIGATION

Aim:

My aim is to investigate if the length and cross-sectional area affects resistance through a circuit.

Back ground scientific knowledge

What resistance is:image00.png

To find the resistance of something we use the following formula:  V

                              Resistance = V                                                    I    Rimage11.png

                                                    Iimage12.png

Resistance is the ratio of potential difference.

As long as I × V and the resistance is constant, and the conductor obeys Ohms Law.  The voltage increases, as long as they increase at the same rate.

 V

image13.png

image14.png

Constant

Temperature

image15.png

                                   I

Ohm’s law

Ohm’s law means that if the voltage is doubled, the current will be doubled. The formula for ohm’s law is the following:

V = I × R

This defines resistance, for Ohmic conductors the resistance is constant, and ohm’s law of proportionality holds.

What causes resistance is:

Resistance of a straight wire depends on:

  1. It’s length- the resistance increases with the increasing length.
  2. It’s thickness- the resistance is greater for thinner wires.
  3. It’s material- good conductors have a lower resistance.

...read more.

Middle

image01.pngimage09.pngimage01.pngimage08.pngimage01.pngimage01.pngimage07.pngimage01.pngimage03.pngimage01.pngimage03.pngimage01.pngimage02.pngimage10.pngimage01.png

image01.png

                                                                                          = Atoms vibrating

Electrons move around the lattice in a random movement, with different speeds and different directions.  They collide with each

Other and the atoms. As they hit into each other the movement is passed on and the vibration increases.  More collisions mean greater resistance and more energy exchange.

Variables

Length: The longer the piece of wire the more collisions there is, and therefore the greater the resistance for a given current.

Cross-sectional area: The narrower the conductor the greater the number of collisions for a given current.

Temperature: the higher the temperature the more vibration in the lattice, the more collisions for a given current.

Material: the material from which the wire is made.

Resistively: resistively is related to the number of factors, which

affect resistance:

  • Number of free electrons
  • Crystallinity in lattice

By reducing crystallinity, it quickens up the flow of electrons and increases collisions, for a given current.

Preliminary work

To help me understand more I have decided to do some preliminary work.  This will help me to research the experiment and explore faults in the experiment.

...read more.

Conclusion

Conclusion

My graphs show that there is a relationship between my voltage and current.  I can see that my results form a straight-line graph, which shows that my results are correct. I can also say that my choice of equipment was correct as I obtained good results. I controlled the variables well throughout the experiment, particularly the temperature.  I did this by switching off the D.C power supply after each result, to keep the temperature down.  I have discovered that the smaller the CSA of the constantan wires, the lower the resistance. I have observed the relationship between voltage, current, and gradient.  The higher the gradient the greater the resistance, which means there must be an increasing voltage and current.  My graph shows that it obeys ohms law, and did not over heat.  Overall it showed to be a success because I obtained a straight-line graph.

...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 the Resistance of a Wire is affected by Cross-Sectional Area

    * A Voltmeter- used to measure voltage. Connected in parallel. * Two different thicknesses of Nichrome wire- used to experiment on. * Two different thicknesses of Constantan wire- used to experiment on. * Meter ruler- used to keep the wire to 20 cm long.

  2. How does the length and cross-sectional area of a wire affect resistance

    Due to this the length increase should be proportional to the resistance increase. Figure 2 The wire above is half the length of the wire in figure 2 and so there should be half the number of collisions between the electrons and the atoms.

  1. The aim of this investigation is to find out the cross-sectional area of a ...

    The material will not change at all and to make sure I will check with the teacher to make sure that all of the wires are the same. The temperature in the room will remain the same and there is not much chance of it changing only due to extreme circumstances.

  2. To investigate how the length (mm) and the cross-sectional (mm2) area of a wire ...

    The other end is said to be at a lower potential and is called the negative end. The function of a battery or other source of electric current is to maintain potential difference. A battery does this by supplying electrons to the negative end of the bar to replace those

  1. Investigate how the cross-sectional area of a piece of wire affects its resistance.

    We will also use five wires, each with a different cross-sectional area, so we get a wider range of results, allowing us to plot a more accurate graph.

  2. My aim is to find out how different cross sectional areas of a wire ...

    So some wire will not be included so I have left five centimetres. I will connect this wire to the circuit using crocodile clips and then I will turn the power on and record the readings of the ammeter and voltmeter and write these values and work out the amount of resistance taking place.

  1. Investigating How the Cross-Sectional Area of a Conductor Affects the Resistance of Current Passing ...

    Use this method to test six lengths of wire with differing cross sectional area. I will make sure that my test is fair by using the same length of wire in at each stage of the experiment. I will control the voltage through the circuit using a variable rheostat.

  2. Physical - Circuit

    First Tried Second Tried Third Tried Length (centimetres) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) Voltage (Volts) Current (amps) 5 0.2 3.5 0.1 2 0.1 2.1 10 0.2 1.8 0.1 1.8 0.1 1.8 15 0.2 1.8 0.1 1.75 0.2 1.75 20 0.25 1.7 0.25 1.8 0.2 1.7 25 0.3 1.7 0.3 1.7 0.3 1.7 30 0.4 1.7 0.35 1.7 0.35 1.7 Length (centimetres)

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