I am investigating “How the resistance changes when the length changes.” Therefore, my input variable is length.
The variables I could have chosen between were the length of the putty, the thickness of the putty, heat or the type of wire/material. I chose to change the length as I felt this would be the easiest and would allow me to get the best results. In order to make the experiment fair, I have to control the other variables.
Thickness I can control the thickness by checking it is the same each time I use a different length. I think that the thicker the putty is, the lower the resistance will be. This is because when you make an object thicker it is as though you are putting a single sheet in parallel. When you put something in parallel it causes the resistance lower. The thicker the object, the more electrons there are. This causes the current to increase and if the current increases, the resistance decreases.