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Ohm's Law and Power · U-I Characteristic and P-R Curve

Simple resistive circuit — adjust voltage \(U\) and resistance \(R\) to see current \(I\) and power \(P\) update instantly

Circuit Parameters

10.0 V
1 V50 V
20 Ω
10 Ω100 Ω

Linear step: 10–100 Ω, step size 1 Ω

Calculation Results

Current \(I = U/R\)
10.00 mA
Auto-convert mA / A
Power \(P = U^2/R\)
0.10 W
Auto-convert mW / W
Ohm's Law: \(U = IR\)   Power: \(P = UI = I^2 R = U^2/R\)

Circuit Diagram

Ohm's Law circuit diagram

Curve Interpretation

U-I Characteristic Curve

A straight line through the origin with slope = \(1/R\). When resistance is fixed, current is proportional to voltage.

P-R Power Curve

\(P = U^2/R\), an inverse hyperbola. Smaller resistance yields greater power.

U-I Characteristic Curve
Linear relationship \(I = U/R\)
● Red dot marks the current operating point (\(U\), \(I\))
P-R Power Curve
Hyperbola \(P = U^2/R\)
● Red dot marks the current operating point (\(R\), \(P\)) | Logarithmic x-axis

Theoretical Basis

Ohm's Law: \(U = IR\), current is proportional to voltage and inversely proportional to resistance.
Joule's Law: \(P = UI = I^2R = U^2/R\), power is proportional to the square of current.
The U-I curve is a straight line through the origin with slope \(1/R\); the P-R curve is a hyperbola \(U^2/R\).

Unit Conversion Notes

• Current: If \(I < 0.1\) A, displayed as mA (×1000); otherwise displayed as A.
• Power: If \(P < 0.1\) W, displayed as mW (×1000); otherwise displayed as W.
• Resistance: Auto-converts between Ω / kΩ (1 kΩ = 1000 Ω).
• Note: High voltage and low resistance produce high current and high power.