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    Question

    Which of the following statements is incorrect for a

    Zener diode in breakdown region?
    A Reverse voltage is greater than breakdown voltage Correct Answer Incorrect Answer
    B Zener voltage remains constant Correct Answer Incorrect Answer
    C Reverse current is limited by series resistance Correct Answer Incorrect Answer
    D Current decreases sharply with increasing voltage Correct Answer Incorrect Answer

    Solution

    In the breakdown region of a Zener diode, the voltage across the diode stays nearly constant at the Zener breakdown voltage, even if the current through it changes. This property is exploited for voltage regulation. However, once breakdown occurs:

    • Reverse current increases rapidly with a small increase in voltage,
    • But voltage stays almost constant, due to the Zener effect or avalanche effect (depending on the breakdown voltage),
    • Series resistance is externally added to limit the current and avoid thermal damage.
    Thus, statement (d) is incorrect because current does not decrease, it increases sharply as voltage attempts to increase beyond the breakdown point.

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