Resistance of a Wire
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Effects change of diameter has on to resistance.
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Introduction
Effects change of diameter has on to resistance.
I am going to be measuring what effect diameter of a wire has on resistance of a wire.
In my prediction I will be considering two equations.
I will have to rearrange this equation to make R the subject. Once I have done this I will get an equation like this.
In this equation R is resistance, A is the cross sectional area, P is the resistivity and L is the length.
In this equation I also need to substitute in the equation for area, therefore the equation will also be linked to diameter of the wire. The equation I will be substituting into the above is.
π.d2
When this is substituted into the equation for resistance it will give me an equation like this.
I am going to be trying to find out the relationship between resistance and diameter. In my experiment I will make a circuit as follows.
A wire is placed into the two crocodile clips and pulled straight. The wire must be of about 1.
Middle
0.56
0.005
1%
0.57
22
0.71
0.7
0.71
0.005
1%
0.71
20
0.92
0.92
0.92
0.005
1%
0.92
18
1.21
1.21
1.22
0.005
0%
1.21
1 | 2 | 3 | ||||||
Voltage (V) | Current (A) | Resistance (Ω) | Voltage (V) | Current (A) | Resistance (Ω) | Voltage (V) |
Conclusion
There are lots of sources of error to be taken into a account, like when measuring out the meter of wire, this wont cause a lot of error but it builds up. Calculating 1/(d/)^2 will create a reasonable amount off error, these all have to be taken into consideration.
I took these sources of error into consideration and to reduce them you could, increase the size of measurement you are taking to reduce the percentage error. Also if I used a analogue ammeter and voltmeter I could have reduced the amount of error. Most of my uncertainties were about 1% so this isn’t massive but it will effect my line of best fit. If I was to reduce my uncertainty’s by taking more time and using more accurate measuring equipment I could have produced a more accurate line of best fit.
For my experiment the overall percentage uncertainty is about 2% calculated to 1 decimal place. This isn’t very big therefore I think my results are reasonably reliable and this relationship I have show is valid.
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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