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Investigating Resistance

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Science Coursework/Investigating Resistance

Michael Hanna


Mr. Dean


Colm, the lab technician, needs some 5 ohm resistors for an experiment but has none in stock. All he has is some Nichrome wire?

Investigate one of the factors which affects the resistance of a wire.

My aim in this investigation is to find out how the length affects the resistance of a wire. f

To understand my investigation I have given some written information supported by scientific knowledge.

To attain the most precise result, a number of factors need to be considered which enables us to achieve this. The variables are:

? Temperature

? Diameter of the wire;

? Material of the wire

Diameter of the wire

By increasing the diameter of the wire we offer more space or routes for the electrons to pass through, therefore meaning fewer collisions with the other ions and less resistance. If the cross sectional area is smaller there will be greater resistance because there will be to more collisions between the ions as there are fewer routes for the electrons to pass through.cobc bcr sebcbcw orbc bck inbc fobc bc.

As the aim is to find out how the length of a wire affects the resistance we have to keep the rest of the variables constant throughout the wire during the experiment. To measure

...read more.




Before I start doing experiments and testing thing I need to predict what I think will happen. My theory is that as the length of the wire increase, the resistance will increase proportionally.
To support my hypothesis I had done a preliminary experiments. to support my prediction. The preliminary showed that as you increase the length of a wire, the resistance also increases.


To acknowledge the equipment needed I used the circuit I used in the preliminary experiment. The following equipment is required:;

  • Connecting wires  
  • Power supply (power pack)  
  • 0-1/0-2 Ammeter
  • 0-6 Voltmeter
  • Crocodile clips
  • 1 meter ruler  
  • Nichrome wire

To perform this experiment I will have to set the circuit that I used in my preliminary experiment.

After setting up the experiment like shown on the next page, in a series circuit. I set the power pack on 4 voltages, and I read the results of the current off the ammeter and the voltage off the voltmeter.

Resistance (Ohms) = Voltage (Volts)


Current (Amps):

This is the formula that I will use to work out the resistance of the circuit. Ohm's law discovered that the amount of steady current through a large number of materials is directly proportional to the potential difference or voltage running across it.

Therefore if the voltage is adjusted it will not

...read more.



From our line of best fit we can see that our results support our predictions and that according to our graph the resistance increases. We can find the constant in the line by finding the gradient of the line:

Gradient= Y1 -Y2


= 190-100


= 90


= 18

The constant is 18, one ohm for every 20 centimeters added to the length. Furthermore our results graph shows all the points fit tightly along out line showing accuracy. As we can see a resistance wire of length twenty centimeters has a resistance of an ohm, 36cm being 2 ohms to prove this. This can be used to find the resistance and can be put in to a formula:


This can also be rearranged to find out the length when given the resistance.

We can see that these are vaguely accurate and can use this as a formula to find the any resistance of wire or the length required to create any resistance. Also this proves my points were accurate and this trend is supported by our research, hypothesis and preliminary work that supports the pattern formed by our results.

I can therefore conclude I have successfully and accurately investigated resistance and how it is affected by lengthening the length of a wire. I have done so with evidence and fair investigation and I believe have successfully completed the investigation to an extent backed up by preliminary work, scientific knowledge, hypotheses and prediction.

...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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