Concept:An ohmic device has a linear \( \text{I-V} \) relationship where resistance remains constant regardless of applied voltage or polarity. A diode deviates from Ohm's law, making it non-ohmic.
Formula:$$I = I_0 \left( e^{\frac{e V}{\eta k_B T}} - 1 \right) \neq \frac{V}{R}$$
Solution:- Under forward bias, current increases exponentially once the knee voltage is exceeded.
- Under reverse bias, current is limited to a small leakage current until breakdown occurs.
- Because its dynamic resistance varies with voltage and depends on polarity, the diode is a non-linear, non-ohmic device.
Why other options are incorrect:- Options B & C: Strict proportionality between voltage and current describes ideal ohmic conductors, not semiconductor diodes.
- Option D: A standard diode does not generate electrical energy on its own; it requires an external source to conduct.
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