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Problem 20 - Olympiad

A p–n junction diode has a reverse saturation current 1 µA at 27 °C. The dynamic resistance for a forward bias 0.2 V is nearest to

Correct: B

r = ηV_T/I₀e^(V/ηV_T) ≈ 0.0259/(10⁻⁶·e^(0.2/0.0259)) ≈ 26 Ω.