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Resistance of a wire investigation.

Free essay example:


The Variables:

Temperature: The higher the temperature, the particles in the wire will become more active which causes the particles to vibrate. This makes it harder for the electrons to pass through the wire. This makes the resistance higher in the wire.

Length: The longer the wire, the particles will have to pass through the wire which requires further energy .This makes it more likely for the electrons to collide with a particle, as there are more of them. This also makes the resistance higher.

Thickness: The thicker the wire, the more spaces there will be between the particles inside it. This means that there is more room for the electrons to pass through so less collisions occur. This actually decreases the resistance of the wire.

Material: There are different materials that you can choose; these options can be Nichrome, Constantan and copper. Different materials have more particles or less particles than others and this is obviously the thing people are going to find out in there preliminary results.

Apparatus:

Why I used it:

Circuit board – With 3 working batteries

Easiest option as it has 3 batteries to use; therefore you can take a result of 1 then 2 then 3 batteries.

3 Wires with crocodile clips either side

Without wires there would be no connection between the wires, batteries, ammeter and Voltage meter.

Ammeter

Records the result of the current so I’ll have to use this to record.

Voltage meter

Records the result of the voltage so I’ll have to use this to record.

Piece of wire (E.g. 30 cm Copper with a weight of 26swg)

This is the main piece of the experiment as you need the material to record the result.

Apparatus:

Preliminary 1 Method:

  1. Gather all equipment shown in apparatus list
  2. Set up the circuit as shown in diagram
  3. Choose what, type andlength of wire you will study first. Measure
    the wire with the metre stick and place the crocodile clips at the
    appropriate places on the wire to connect the resistance wire into the
    circuit.
  4. Switch the power supply on, and record the ammeter reading and the
    voltmeter reading in a table from 1 battery to all 3.
  5. Record the readings shown on the ammeter and voltmeter and repeat with different lengths of wire. E.g. 10 , 15 , 20 , 25 & 30

Use the formula R = V/I to get the resistance of the results.

image00.png

Preliminary 2 Method:

  1. Set up the circuit like in the diagram below again.
  2. Choose what, type andweight of wire you will study first. Choose
    the wire and measure a length for e.g. use 30cm for every different weight and once again place the crocodile clips at the appropriate places on the wire to connect the wire into the circuit.
  3. Switch the power supply on, and record the ammeter reading and the
    voltmeter reading in a table from 1 battery to all 3.
  4. Record the readings shown on the ammeter and voltmeter and repeat with different weights of wire. E.g. 24, 26 & 32.

image01.png

Conclusion:

 Looking firstly at my first set of Preliminary results they show me that they are quite unreliable as from the Ammeter results (Current) they are unreliable as from the one cell results (Ammeter) they show that they start at 1.58 then drop to 1.40 then suddenly jump up to 1.70 so this shows that I’ve either incorrectly done the experiment or have a outlier as then the results stay similar which I find very weird however with the voltage it looks reliable as it starts at 0.11 (one cell) and it goes down to 0.04 with a reliable pattern as there are no random results. Due to these preliminary results I feel these results do have a few outliers particularly from the current results.

Looking now at the 2nd set of results these also show odd results as from my own viewpoint it looks as if 26 swg should be the middle value of 24 & 32 however 26 is always higher or lower than the other 2 weights . This may have been at the fault of a faulty battery but when we complete the real tests this is something we will control.

Main Method:

  1. Collect equipment and set it up, following circuit diagram.
  2.   Turn voltmeter and ammeter on.
  3. Turn power supply on.
  4.  Record the voltage and current, so it’s possible to work out the resistance.

Firstly collect all your equipment

  1. 1 Digital Ammeter
  2. 1 Digital Voltmeter
  3. 5 Wires
  4. Length of Wire (1 meter)
  5. 2 Crocodile Clips
  6. Circuit board
  7. 1 Meter Ruler
  8. Constantan 26,30,32,34&36 (This is what I’ve chosen)
  1. Then make up the circuit like shown in the diagram
  2. Collect the first size of (constantan in my case)
  3. When you’ve set the circuit up , connect the constantan in place to measure
  4. Record the resistance of 1 battery then 2 then 3.
  5. Record the results in a table
  6. Repeat the experiment 4 more times with the other 4 measurements

image02.png

Conclusion:

Looking at my results I feel they are mixed, some good and some poor. Looking at the results of 26, 30 & 34 constantan, these results look very reliable as in my graphs the line of best fit is perfect whereas constantan 32 has a much lower result in the current section and in constantan 36 the graphs shows there is a negative correlation but I did do my experiment how I was meant to but not with the intensity I could have completed it to as there are outliers in my results which probably could have been prevented.

Also looking at my graph there seems to be a trend at the begging however as it comes towards the end of plotting it the trend loses place. The first 3 results slope down which is right however the last 2 plotted points rise back up which shouldn’t of happened. This may have occurred due to several things including:

  • The measurement of the wire
  • Controlling the temperature

I will say how I could of used these factors to improve the results I got.

The thing that I have learnt the most is probably measuring the wire. I feel that I had not pulled the wire tight enough to make it completely straight ,  therefore when measuring it was a bit bendy and curly and the measurement was likely to be around 32 or 33 NOT 30cm.

I feel the best option was probably to re-do the test of 32 to improve the reliability as it was out of sync with the other results. However I feel the results may have come down to sloppiness as I remember rushing this result and I think the measurement was probably un-accurate like I stated before.

Overall I definitely feel that more results are needed as I feel too many results are outliers , but if I was to do this again I would do the results twice just to make sure they are reliable as I’m still not sure whether my results are 100% reliable.

Evaluation:

Could I have done better?

Yes, Yes I do feel that I and my partner could have done better by doing the same weight of Constantan in the same lesson rather than different ones on different days. The thing that made the experiment tricky was controlling the temperature as there were only little chances of doing this which I and my partner did not know. Therefore if we did the experiment again then we’d also focus on keeping the temperature the same. We could have put the circuit board in ice to keep the temperature cool and that was the only real we could have achieved this. Due to feeling that there were features missed out I will know reconstruct my main method to what it should look like:        

  1. Firstly collect all your equipment
  • 1 Digital Ammeter
  • 1 Digital Voltmeter
  • 5 Wires
  • Length of Wire (1 meter)
  • 2 Crocodile Clips
  • Circuit board
  • 1 Meter Ruler
  • Constantan 26,30,32,34&36 (This is what I’ve chosen)
  • Bath of ice
  1. Then make up the circuit like shown in the diagram
  2. Collect the first size of (constantan in my case)
  3. When you’ve set the circuit up ,place the circuit board in the ice to keep cool and measure temperature so you know what temperature to keep it at
  4. Place  the constantan in the crocodile clips to measure resistance
  5. Record the resistance of 1 battery then 2 then 3.
  6. Record the results in a table
  7. Repeat the experiment 4 more times with the other 4 measurements

Reliability of data:

My results do have their positives and negatives as on my line of best fits there are points that are not close to it and then on others they are close to the line of best fit. So judging from this I would say there are outliers and I would brand my results as UNRELIABLE. The thing that may have caused this could be again to temperature or faulty equipment which is very hard to judge at the time of working

Reliability of conclusion:

My conclusion is RELIABLE because looking at my new method I do feel it is now correct and shows the right steps towards doing the experiment, also looking at the scatter in my graphs they do show signs of some closeness and again some don’t but in my conclusion I have responded by saying how they are not reliable and have stated why there not reliable due to this my conclusion shows sign of progression in making the experiment better and finally more controllable therefore I think my conclusion is reliable.

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