B5 practical: Factors affecting R (pencil) example results
To vary the area multiple lines were drawn next to each other on the paper. Each line had width of 0.5 mm. The cross sectional area of the line is proportional to the number of lines drawn so 1/n was calculated to test if R was proportional to 1/A. A graph of R vs 1/n was then plotted This gives quite a good correlation. Gradient = 627 kΩ According to the formula R = ρL/A = ρL/nwtwhere w = the width of one line...