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How the length of wire affects the current flowing through it

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GCSE Physics Coursework; How the length of wire

Affects the current flowing through it


The aim of this investigation is to find out how the length of a piece of wire affects the current flowing through it.

Equipment Required

  • Test wire
  • Voltmeter
  • Power supply (0-10v DC)
  • Crocodile clips
  • Ammeter
  • Variable resistor
  • Ruler




How it should affect the dependant variable and why

Length of wire

The length of wire affects the current because the longer the wire, the more energy the electrons have got to use to overcome the resistance so the current is less


As V=IR (ohm’s law)

...read more.



Some materials are denser than others and some are better conductors, therefore there are different amounts of free electrons, so will be different levels of resistance

The dependant variable (what I will be measuring) is current.


I will arrange the apparatus as shown in the diagram and cut wires to the following lengths: 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm and 100cm. I will attach each piece of wire, in turn, to the crocodile-clip leads and set the voltage to 0.4 Volts. This was kept constant throughout the experiment. I will repeat this 3 times for each length of wire and take an average.

I will take 10 readings and my

...read more.


The aim is to ensure that the current can always be read to 2 significant figures, i.e., I > 0.10 A, when L = 1000m.

To ensure that the wire chosen does not get hot, i.e., current I < 1.5 A when L = 10.0 cm

Voltage (V)


Current at 10.0 cm (amps)

100.0 Amps



SW6 Constant 30



Gets too hot at 10cm, therefore not suitable


From this experiment I have discovered that the over all resistance in a piece of wire is directly proportional the length of the wire. As the length of the wire increases, the resistance increases proportionally.

I have drawn a graph to display my results. My graph is accurate with a best-fit line and anomalous points highlighted.

The trend in my graph indicates as the length of the wire is more, the current becomes less. Mathematically,

...read more.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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