Electrical conductivities of different grade lead pencil graphite

Graphite is not only a substance that are used in lead pencils, it can also be used as a conductor. In the 21st Century, carbon allotropes and alloys are used in many industrial areas, therefore carbon is an important element to be examined. The investigation aims to deduce the conductivities of different types of lead pencils. In this extended essay, I investigated the relationship between electrical conductivity and pencil grade in graphite conductors under the research question of "How does the grade of a drawing pencil in HB scale affect the electrical conductivity of the pencil?". To explore this relationship, I used pencils of same brand but different HB grades. I used one sample from each of the seven different pencil grades. I connected each sample to a DC supply in series separately and measured how much current they carry under 2.0V of potential difference. To outline the process of the investigation after determining the problem, I first designed the experiment mechanism. Then I collected the data and built data tables. After interpreting the data mathematically, I analyzed it and drew conclusions. I connected each pencil to the DC Power Supply and performed 12 trials for each pencil grade. In the end, there were 12 data for each of the 14 pencil grades. Having a total of 168 data, I calculated the mean current values for each of the pencils. Then I used resistance formulae to calculate the electrical conductivity of the pencils. I built a table to sketch a graph using Logger Pro 3 and drew my conclusions using these two statistical items. As my conclusion, I deduced that increasing H scale decreases the conductivity of the pencil because of the decreasing amount graphite used while increasing B scale increases the conductivity of the pencil because of the increasing amount of graphite