Electronics · Semiconductor devices / Principles and inquiry
Diode current–voltage characteristics experiment guide
Apply voltage to a diode and series resistor and record the actual device voltage and current. Compare forward and reverse bias.
How does it work?
Forward current increases sharply and is limited by the series resistor. Threshold voltage depends on the chosen reference current.
I = Is(exp(Vd/(nVT)) − 1) · Vin = IRs + Vd
Try this investigation
- Sweep the applied voltage from negative to positive and watch the signs of device voltage and current.
- Run and record each of the three baseline presets.
- At the same applied voltage, change only the device or temperature.
Interpreting your results
What current flows with −5 V reverse bias on a silicon diode when breakdown is omitted?
Reverse current near zero
Assumptions and limitations
The model uses the Shockley equation and a 100 Ω series resistor. Reverse breakdown, self-heating and LED efficiency are omitted. Temperature affects only VT, so real temperature dependence differs. Use this simulation; do not reproduce it with real power supplies or wall outlets.