Tap the battery or the resistor to change its value live.
Vs0.00 V
Vd0.00 V
I0.00 mA
I–V characteristic
Knee voltage (I = 1 mA) ≈ —
Observation table
| No. | Vs (V) | Vd (V) | I (mA) | |
|---|---|---|---|---|
| No readings yet — set a voltage, then tap + Record reading. | ||||
Procedure & theory
Aim: To study the forward characteristics of a p-n junction diode and find its knee voltage.
Circuit: A variable DC supply Vs in series with resistor R (1 kΩ) and the diode D, cathode to ground.
- Set Vs = 0 V. Tap + Record reading to log Vs, Vd and I.
- Raise Vs in steps of 0.1 V up to about 1.5 V, recording each step.
- Take smaller steps (0.05 V) where the current starts rising fast.
- Optionally try negative Vs to observe the reverse-bias region.
- Plot I vs Vd from the table; the knee voltage is where current rises sharply (here, Vd at I = 1 mA).
Model: silicon diode, I = Is(eV/nVT − 1), Is = 1.7×10−15 A, n = 1.