Resistors and Ohm's Law Video Lessons

Concept

# Problem: Pencil "lead" is actually carbon. What is the resistance of the 0.760 mm-diameter, 7.00cm-long lead from a mechanical pencil?

###### FREE Expert Solution

Resistance:

$\overline{){\mathbf{R}}{\mathbf{=}}{\mathbf{\rho }}\frac{\mathbf{l}}{\mathbf{A}}}$ where ρ is the resistivity, l is the length, and A is the cross-sectional area.

A = πr2

###### Problem Details
Pencil "lead" is actually carbon. What is the resistance of the 0.760 mm-diameter, 7.00cm-long lead from a mechanical pencil?