An investigation to see how well carbon putty conducts electricity.

Equipment:

Coins x 2

Carbon putty

Ammeter

Voltmeter

Wires

Power pack

Variable resistor

Calliper

Tile

I will perform this investigation in a safe a fair way.  I will not leave the power on unattended and I will keep all the factors the same apart from the one I decide to change.  I will change the length of the putty.

The factors I will have to keep constant are the diameter of the putty, temperature, the wires, size of coins.

Prediction and theory

I predict that the longer the putty is the more resistance it will have and therefore will not conduct the electricity as well.  This is because the putty has free moving electrons in which the electricity jumps between in order to get through it.  Having these free moving electrons lets the putty conduct the electricity.  But if the putty is longer and the diameter kept constant then there will be more free moving electrons in the putty, this mean that for the electricity to be conducted through the putty the energy has to jump between more electrons making the resistance of the putty larger.  When the length of the putty is small then there are less free moving electron which pass the electricity and therefore not as many for the electricity to jump through in order to conduct.

Preliminary work:

This preliminary work was done before my investigation and it helped my determine what width I should use for the diameter.  For this experiment I kept everything constant but changed the width of the diameter.  These are the results from my preliminary work.

My investigation proves my theory that the longer the putty is, the more resistance there will be.  The electricity took longer to jump through the free moving electrons to go through the putty.  Therefore when the putty is shorter the resistance is less as there are less free moving electrons for the electricity to pass through.  You can see this is true from all my graphs.

Evaluation:

As my results were accurate and proved my theory there is not much that could be done to improve it.  However, I could investigate the resistance of the lengths in between the ones that I did and I should also use some kind of mechanism so that I would know that the diameter was the same throughout the putty.  This would make the results more reliable although my results were reliable enough to prove my prediction.  

I think that I worked well on my investigation and completed it within the time specified.  I worked carefully and safely.

To investigate further in this work I could experiment with temperature or changing another factor.  This would be interesting to see how all the factors would effect the resistance of the carbon putty.