• 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...




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


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.








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.




                                                                                          = 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.


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.



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. Physical - Circuit

    Table 5: This table shows the details about normal wires used in the experiment, Constantan wire with diameter of 0.90mm, however is longer than the one before, retry. First Tried Second Tried Third Tried Length (centimetres) Voltage (Volts) Current (amps)

  2. AimTo investigate the variables that affect resistance in an electric circuit.

    The unit of conductance is the mho, or ohm spelled backward, and the symbol is an inverted omega, ~~. The resistance of an object is also determined by the nature of the substance of which it is composed, known as the resistively, the dimensions of the object, and the temperature.

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

    0.14 18.3 18.4 18.1 18.3 0.102 0.36 2.23 2.23 0.17 0.17 0.17 13.1 13.1 13.0 13.1 0.385 0.7 1.98 1.99 1.99 0.32 0.32 0.32 6.19 6.22 6.22 6.21 Key: Anomalous result ANALYSIS: Conclusion- My results tell me that as the cross sectional area increases, the resistance decreases, but this only

  2. Investigate how the cross section of a wire affects the resistance in a circuit.

    3. Cross Section- My prediction is that the bigger the cross section is, the less resistance will be produced. 4. Material- The material used for the wire is a very important factor that has to be taken in account for, because the resistance of a wire depends on the factor called resistivity.

  1. Investigating Resistance– To investigate if and how a wires length affects the resistance.

    For ordinary currents, this drift velocity is on the order of millimetres per second in contrast to the speeds of the electrons themselves which are on the order of a million meters per second. Even the electron speeds are themselves small compared to the speed of transmission of an electrical

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

    the line of best fit in all the graphs apart from some anomalies. To improve these results it would help to take the first measurement on the ammeter and the voltmeter before the wire begins to heat or to keep the wire cooler by either cooling the room or by

  1. 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.

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

    Resistance is caused when these electrons flowing towards the positive end have to jump atoms. The more difficult it is for the electrons to move the higher the resistance. So the larger the cross sectional area the larger the space for the electrons to move about in meaning not a

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