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How I will record my results.
I will record my results in a table like the following with these titles. My table clearly shows how many different lengths I will use, and will repeat the experiment 3 times with each different length. I will use the following voltages
Below is a sketch in which my graphs will be presented with the following titles and labeling.
Observations.
Now having conducted the experiment according to my method outlined in section 1. I followed my method using all the safety precautions.
Trend
From my results, I noticed the following trend.
As I double the length of the nicrome wire, I double the resistance. This is very obvious from my table of results.
These results clearly show now as we double the resistance we double the resistance and as we treble the length, we treble the resistance.
E.g. A length of 30cm=resistance of 3
A length of 60cm=resistance of 8
From this you can see that the resistance did double, but I have an anonymous result at 60cm, as it did not double exactly , this could have been caused by a human error, refer to the analysis of results for more detail on this.
3d Diagram
The following is a 3d diagram of the experiment in which I conducted to find the resistance of a piece of nicrome wire.
Circuit diagram
The following is a circuit diagram of the experiment in which I conducted.
Analysis of results.
Now having carried out the experiment, and got accurate results. I know my results are accurate as I repeated the experiment three times, but if I were to repeat the experiment again I would use different lengths.
Prediction
I predict that as I increase the length of the nicrome wire I increase the resistance, so as double the length of the wire I double the resistance, treble the length, treble the resistance. From my scientific back round I stated that the resistance is directly proportional to the length, i.e.-R=L/A.
Variables
To make this experiment a fair test we must consider 3 variables
1.Constant-We will always keep the temperature constant and will always use nicrome wire
2.Change-We will change the length of the nicrome wire.
3.Measure-We will measure the current and voltage reading to find the resistance.
Ammeter/Voltmeter method
Below is a sketch of the circuit that will be used in our experiment, this is referred to the Ammeter/Voltmeter method. Ammeter is measured in amps (A), and the voltmeter is measured in voltage (v). the ammeter runs in series and the voltmeter runs in parallel.
Sketch
Method
* Collect all the apparatus required.
* Measure out the lengths of the nichrome wire.
* Cello tape a piece of nichrome wire to each end of the ruler.
* Connect the two shunts to the mA and the voltmeter then connect wires to them.
* Switch the power supply to 0 before switching on.
* When putting the power supply on, turn the knob slowly until the reading of the voltmeter reads at 0.1.
* Now record the results of this reading and carry this process out for each reading.
* Remember to turn the power supply off each time, to prevent the wire heating up as this can be dangerous.
Equipment list
*Milli Ammeter (d.c)-0.100mA
*Voltmeter (d.c)
*2 Analogue meters
*Power pack
*Connecting wires
*Crocodile clip
*Nichrome wire
*Cello tape
Table of Results
Analysis of Results
Now having carried out the experiment on how to find the resistance of nichrome wire and got fairly accurate results. I will now analyse my results.
On my graph I drew a best line of fit and found one of the results were anonyms as it didn’t fit onto this line. This could be due to a human error such as me incorrectly recording my results or the nichrome wire was not straight when measuring the resistance. Also the nichrome wire could have been overheated.
My results, from conducting the experiment were fairly accurate a I repeated the experiment three times for each different length of nichrome wire.
If I were to repeat the experiment again I would take more results so I would be sure that my results were reliable, make sure at all times that the nichrome wire was perfectly straight, or could measure the temperature of the nichrome wire by putting it into a water bath, as when I was conducting the experiment I just assumed the temperature at room temperature.
Graph
Now having completed my graph showing length of nichrome wire via average resistance, I found it supports my earlier prediction as there is a straight line through the origin and the length of the nichrome wire is directly proportional to the resistance of the wire.
As you can see from graph I have drawn in different color lines to prove my prediction is correct.
I.e. Length=30 Average Resistance=4
Length=60 Average Resistance=9
