- Asked 4/28
- 2070 Ashad · 6 marks
Diode circuit current, eta 1.74, 6 V
Short answer
Using iterative KVL and diode equation, the diode voltage converges to 0.79 V. The circuit current is I = (6 − 0.79) / 660 ≈ 7.9 mA.
In the given circuit, the diode used has its η = 1.74 and it conducts 1mA at forward bias voltage of 0.7V. Find the current flow in the circuit. [Figure: V = 6 V source in series with R = 660 Ω and a diode D, current I = ?]
The circuit is a source in series with a resistor and a diode. Use the diode equation with KVL and iterate.
Given
V = 6 V, R = 660 Ω, η = 1.74, ID = 1 mA at 0.7 V, VT = 25 mV, so η VT = 43.5 mV.
Equations
VD = 0.7 + η VT ln(I / 1 mA) = 0.7 + 0.0435 ln(I/1 mA)
I = (6 - VD)/660
Iteration
| Step | VD guess (V) | I = (6 - VD)/660 (mA) | New VD (V) |
|---|---|---|---|
| 1 | 0.700 | 8.030 | 0.7907 |
| 2 | 0.7907 | 7.893 | 0.7899 |
| 3 | 0.7899 | 7.894 | 0.7899 |
Converged: VD = 0.790 V.
I = (6 - 0.790)/660 = 7.89 mA
Answer: I ≈ 7.9 mA (VD ≈ 0.79 V).
✓ Answer checked by Claude Opus 5.5 (high effort)
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