12) Then work out resistance R=V/I
Range And Numbers
I will be taking results every 20 cm over the metre of wire, which means I will have 5 sets of results.
Fair Test
To make this a fare test you must use the same apparatus, the same type of wire (nichrome) and from the same reel, so the only thing in the circuit that is changing is the length of the nichrome wire. Also you must keep the room at the same temperature, as it was when you started.
Safety
Be careful with the wire cutters so not to cut yourself, make sure there is nothing to trip over, have a fire extinguisher handy (MAKE SURE IT ISN'T WATER, WATER BASED, OR ANY WATER NEARBY BECAUSE THE FIRE MIGHT OR WILL BE AN ELECTRICAL FIRE AND WILL MAKE THE FIRE WORST AND PUTS YOU AT EVEN MORE RISK).
Precision and Accuracy
- Make sure the results you collect are correct; make sure you measure the nichrome wire with a ruler to exactly 1 metre (100 cm, or 1000 mm) and cut it accuracy with the cutters due to this will affect your results.
- Make sure the nichrome wire is the same thickness because it will affect the resistance as well.
- Make sure the power pack is on 6V precisely, or this too will affect your results.
- Make sure all the leads are the same size and length.
- Make sure you have the digital voltmeter (which is more accurate then a needle voltmeter because it is accurate to 2 decimal places) in the right place, which is in parallel with the nichrome wire.
- Use all the same equipment that u have used all along accept for the nichrome wire.
- Keep room at same temperature throughout the experiment.
My Prediction
My prediction is that when the length of the wire is increased so does the resistance of the wire and so the current decreases. This is caused by the amount of nuclei in the wire. When the electrons pass through the wire they hit the protons and rebound and hit more protons and so this will happen till it gets back to the energy source. This I’d all shown by the diagram below.
Also if the temperature of the room is increased then the resistance will to, because the nuclei start to vibrate more. The wire will also start to heat up if you turn up the voltage too much, the wire will also start to heat up, so that is another reason to not turn up the voltage.
You work out the resistance by using the formula:
R (Resistance)= V (Voltage)/ I (Current).
Preliminary Experiment
I have carried out the experiment and it works, and my prediction was correct, but however what I did not know would happen is that the voltage would increase.
There is a good gap between the results, of which the biggest value is 4X bigger than the smallest value.
So to recap the kit I used in the experiment: a digital voltmeter, a digital ammeter, a voltage of 2 volts from a power pack and 1 metre of nichrome wire.
The reason I have decided to use the digital ammeter is because it is accurate to 2 decimal places, which is very accurate, and also I am using a digital voltmeter because that too can also be accurate to 2 decimal places and this is why I’m not using the needle versions, which could measure to the nearest 0.5 volt or amp.
I have used the nichrome wire because it has a higher resistance then the copper wire, has an almost Zero resistance, so nichrome wire was used to give a more positive resistance.
The Experiment Results
Analysis
when the length of the wire is increased so does the resistance of the wire and so the current decreases. This is caused by the amount of nuclei in the wire. When the electrons pass through the wire they hit the protons and rebound and hit more protons and so this will happen till it gets back to the energy source. This I’d all shown by the diagram below.
Evaluation
Accuracy: the voltmeter and ammeter were accurate to two decimal places, which is very accurate, and the wooden ruler used was also accurate, to the mini meter. The power pack wasn’t accurate and was set to the right voltage using the voltmeter; however I didn’t always use the same equipment so some of my results were a bit out.
Anomalous results:
I had no anomalous results.
Reliability:
My results were very close the largest range was 0.11.
Improvements:
- Use a more accurate ruler.
- Spend more time on actual experiment.
Justify: My results do in deed justify my conclusion.
