Electronics
Resistivity from a measurement
Scales the measured resistance by the geometry of the sample.
The Formula
rho = R x A / L
Scales the measured resistance by the geometry of the sample.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| rho | Resistivity | ohm metres | The material property. |
| R | Resistance | ohms | The resistance measured across the sample. |
| A | Cross sectional area | square metres | The area the current flows through. |
| L | Length | metres | The length over which resistance was measured. |
What Each Symbol Means
rhoohm metres
Resistivity
The material property.
Rohms
Resistance
The resistance measured across the sample.
Asquare metres
Cross sectional area
The area the current flows through.
Lmetres
Length
The length over which resistance was measured.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate resistivity page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Resistivity, filed under Science. Every number the guide produces comes from substituting into this one line.