Find resistivity from V-I graph data and diameter. See slope, resistance, area, and conductivity instantly. Built for physics homework, experiments, reports, and exam practice.
The slope of a V versus I graph gives resistance when voltage is on the vertical axis and current is on the horizontal axis.
Resistance: R = ΔV / ΔI
Cross-sectional area: A = πd² / 4
Resistivity: ρ = RA / L
Conductivity: σ = 1 / ρ
Here, d is wire diameter and L is wire length. The calculator converts units before solving. That improves consistency for lab work and exam preparation.
Enter two points from the straight portion of your V-I graph. Use matching current units for both points.
Enter the tested wire length. Then enter the wire diameter and choose its unit.
Click the calculate button. The result appears below the header and above the form.
Review resistance, area, resistivity, and conductivity. Then export the result as CSV or PDF if needed.
| Sample | V1 (V) | I1 (A) | V2 (V) | I2 (A) | Length (m) | Diameter (mm) | R (Ω) | ρ (Ω·m) |
|---|---|---|---|---|---|---|---|---|
| Wire A | 0.20 | 0.10 | 1.00 | 0.50 | 1.20 | 0.50 | 2.00 | 3.27e-7 |
| Wire B | 0.30 | 0.10 | 1.80 | 0.60 | 1.00 | 0.40 | 3.00 | 3.77e-7 |
| Wire C | 0.40 | 0.20 | 2.00 | 1.00 | 0.80 | 0.30 | 2.00 | 1.77e-7 |
This resistivity calculator helps students estimate wire resistivity from a V vs I graph. It uses graph slope, wire diameter, and wire length. That makes it useful for physics labs, assignments, and revision tasks. A straight line on the graph usually means resistance stays nearly constant. The slope then represents resistance. Once resistance is known, resistivity can be found from the wire geometry. This page also reports cross-sectional area and conductivity. Those values support deeper analysis and quicker lab reporting. The calculator accepts different units for current, length, and diameter. That reduces manual conversion mistakes. It is helpful when you want a clean and repeatable answer.
In an ohmic conductor, voltage changes directly with current. The V-I graph becomes a straight line. The slope of that line equals resistance when voltage is plotted against current. This is why two points from the graph can estimate resistance. The calculator uses the change in voltage and the change in current. It then converts the current to amperes before solving. This small step is important. Wrong current units can create very large errors. The resistance value also helps you check whether your graph is reasonable. A stable slope usually suggests better experimental consistency and cleaner observations.
Resistance alone does not describe the material. A thick wire and a thin wire can have different resistances even if both are made from the same material. Resistivity corrects for geometry. The formula uses wire area and length, so diameter matters directly. Because area depends on diameter squared, even a small diameter error changes the final answer. Accurate measurement improves your result a lot. Length also matters because longer wires resist current more strongly. When both values are included, the answer reflects the material property better. This makes the calculator useful for comparing wires, checking lab results, and preparing for physics questions on current electricity.
The slope represents resistance when voltage is plotted on the vertical axis and current on the horizontal axis. A steeper slope means a larger resistance value.
Diameter gives the wire cross-sectional area. Resistivity depends on resistance, area, and length. Without diameter, the material property cannot be calculated correctly.
Yes. This calculator supports A, mA, and µA. It converts the selected current unit to amperes before calculating resistance and resistivity.
The calculator uses absolute changes in voltage and current. Reversing the two points will not change the final resistance and resistivity values.
The main result is shown in ohm metre, written as Ω·m. The page also shows Ω·mm²/m for common lab comparison.
It works best for straight-line regions of the graph. If the graph is curved, choose two points from a small linear section only.
Conductivity is the reciprocal of resistivity. It helps compare how easily different materials allow electric current to pass through them.
Yes. It is useful for homework, practical notebooks, and report checking. The export options also make it easier to save calculated values.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.