The Pouillet's Law Length calculator use Pouilet's Law (R = ρ • L/A) to compute the length required to achieve a resistance of an object with uniform cross-section and materials based on resistivity of material and cross-section area of the resistive material.
INSTRUCTIONS: Choose units and enter the following:
- (ρ) Reistivity (units: ohm-meters (Ω⋅m))
- (A) Cross-section Area
- (R) Resistance over Length
Length (L): The length is returned in meters. However, this can be automatically converted to compatible units via the pull-down menu.
Resistivity and Conductivity
When cross-section area and physical composition of material are consistent (uniform), 
which is an ideal case, the resistivity of a material is an intrinsic property of a material. Many conductors and resistors are manufactured with uniform materials and cross-sections making a useful application of the concept of resistivity. This relationship between resistivity and resistance is described in Pouilet's Law for Resistivity in the following formula:
where:
- ρ = resistivity
- R = electrical resistance
- A = cross-section area
- L = length
Pouilet's Law is named after physicist Claud Pouillet (born 16 Feb 1790, died 14 Jun 1868 , a member of the French Academy of Sciences.