# Investigate how the resistance changes when the length changes of a peice of putty

Rahee Suchak

10A

PHYSICS COURSEWORK

Conducting Putty

PLAN

I am investigating “How the resistance changes when the length changes.”  Therefore, my input variable is length.

Variables:

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.

A diagram to show why, when the putty is thicker, the resistance will decrease.

Type of wire/material        I can control the type of wire/material by not changing it throughout the experiment and by using the same piece of putty each time.  The theory behind what would happen would depend on what materials you use and what their properties are.

Heat        Heat is the key variable and in order to control it, you have to control the current.  In order to control the current, you need a rheostat.  The higher the ...