Method
Set the voltage from power supply to 6V
Set the length of a wire to 40cm. Measure length as accurate as possible.
Record Current as well as P.D 3 times, in 2 decimal places for get accurate answer.
Change the thickness of a wire (18, 20, 24, 26, 32, 36, 38 in SWG unit) 7 times.
Apparatus
Power supply, Voltage meter, anemometer, 2 clips, some electric wire (copper wire) and Nickel chrome wire (18, 20, 24, 26, 32, 36, 38 in SWG unit).
Diagram
Results
Conclusion
As you can see in the graph, when the diameter of a wire is getting smaller which means a wire is getting thinner, the resistance goes up. Also, when the diameter of a wire is getting higher that means a wire is getting thicker, the resistance goes down. The trend line tells us this graph is inversely proportional.
My hypothesis was generally right. However, I never sure about how comes it happened.
As a result, we confirm that the square of resistance of a wire is inversely proportional with thickness of a wire.
Thickness of a wire ∝ 1 / (Resistance) 2
Evaluation
Our experiment was quiet good, because we weren’t faced on any big problems. However, one thing I just want to mention is, when we deal with 18 SWG and 20SWG wire, the wire gets really hot even we could smell something burning.
Although we set the length of a wire to 40cm, it wasn’t enough for thick wire such as 18 SWG and 20SWG wire.
Another small problem was the wires weren’t straight. So the length of a wire might be inaccurate, it could be effects to get an accurate value for resistance of wire. Especially, thick wire was really hard to make it straight.
Suggestions
Solution for first problem is, do the experiment in the water, because water can remain cool. But it seems to be a dangerous.
Solution for second problem is, use the hammer, this solution seem to be useful for only thick wire.
