Linear vs Nonlinear I-V Characteristics
Description
This MicroSim displays two I-V graphs side by side. The left panel shows the linear I-V characteristic of a resistor — a straight line whose slope equals 1/R. The right panel shows the exponential I-V characteristic of a diode using the Shockley equation. A shared voltage slider moves a red dot along both curves simultaneously so students can directly compare how each element responds to the same applied voltage.
Key Concepts
- A linear element (resistor) obeys Ohm's Law: \(I = V/R\), giving a straight-line I-V curve.
- A nonlinear element (diode) follows the Shockley equation: \(I = I_S(e^{V/V_T} - 1)\).
- The thermal voltage \(V_T \approx 25.85\) mV at room temperature governs the diode's exponential turn-on.
- A diode conducts significant current only above its forward voltage (~0.6 V for silicon).
- The concept of small-signal resistance arises from linearizing the diode curve around an operating point.