- Asked 4/28
- 2072 Chaitra · 4 marks
Diode circuit current, eta 1.74, 10 V
Short answer
Iteration with VD=0.7+0.0435 ln(ID/1mA) and ID=(10−VD)/500 gives VD≈0.827 V, ID≈18.35 mA.
In the given circuit, the diode used has its η = 1.74 and it conducts 1mA at forward bias voltage of 0.7 V. Find the current flow in the circuit. [Figure: V = 10 V source in series with R = 500 Ω and a diode, current ID = ?]
Use the diode's exponential law and KVL, and iterate.
Given
V = 10 V, R = 500 Ω, η = 1.74, ID = 1 mA at 0.7 V, VT = 25 mV, so η VT = 43.5 mV.
Equations
VD = 0.7 + 0.0435 ln(ID / 1 mA)
ID = (10 - VD)/500
Iteration
| Step | VD guess (V) | ID (mA) | New VD (V) |
|---|---|---|---|
| 1 | 0.700 | 18.600 | 0.8272 |
| 2 | 0.8272 | 18.346 | 0.8266 |
| 3 | 0.8266 | 18.347 | 0.8266 |
Converged at VD = 0.8266 V.
ID = (10 - 0.8266)/500 = 18.35 mA
Answer: I ≈ 18.35 mA (VD ≈ 0.83 V). The constant-drop (0.7 V) estimate would be 18.6 mA, close to this value.
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Diode circuit current, eta 1.74, 6 V · Electronics Devices and Circuit, chapter 1 · asked 4×
- Diode circuit current, eta 1.74 · Electronics Devices and Circuit, chapter 1 · asked 4×
- Diode current at 100°C (eta 1.8) · Electronics Devices and Circuit, chapter 1 · asked 4×
- Diode current and voltage, VDD 5 V, R 1 kΩ · Electronics Devices and Circuit, chapter 1
- Diode current and voltage, 0.1 V per decade · Electronics Devices and Circuit, chapter 1