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Series resistance for safe operation of a Zener diode from its maximum power or current

This type of question, asked 6 times: 2021 Paper 21, 29 Jul 2022, 10 Apr 2023, 1 Feb 2024, 24 Jan 2026 S1, 4 Apr 2026 S2. All 6 questions below, oldest first.

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  1. Question 1

    2021 Paper 21

    24
    A zener diode of power rating 2 W2\text{ }W is to be used as a voltage regulator. If the zener diode has a breakdown of 10 V10\text{ }V and it has to regulate voltage fluctuated between 6 V6\text{ }V and 14 V14\text{ }V, the value of RsR_{s} for safe operation should be ____\_\_\_\_ Ω\Omega.

  2. Question 2

    29 Jul 2022

    118
    A 8 V8\text{ }V Zener diode along with a series resistance RR is connected across a 20 V20\text{ }V supply (as shown in the figure). If the maximum Zener current is 25 mA25\text{ }mA, then the minimum value of RR will be ____\_\_\_\_ Ω\Omega.

  3. Question 3

    10 Apr 2023

    3
    A zener diode of power rating 1.6 W1.6\text{ }W is to be used as voltage regulator. If the zener diode has a breakdown of 8 V8\text{ }V and it has to regulate voltage fluctuating between 3 V3\text{ }V and 10 V10\text{ }V. The value of resistance RsR_{s} for safe operation of diode will be:

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  4. Question 4

    1 Feb 2024

    3
    In the given circuit if the power rating of Zener diode is 10 mW10\text{ }mW, the value of series resistance RsR_{s} to regulate the input unregulated supply is:

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  5. Question 5

    24 Jan 2026 S1

    23
    A voltage regulating circuit consisting of Zener diode, having break-down voltage of 10 V and maximum power dissipation of 0.4 W , is operated at 15 V . The approximate value of protective resistance in this circuit is ____\_\_\_\_ Ω\Omega.

  6. Question 6

    4 Apr 2026 S2

    21
    A diode has Zener voltage of 10 V and maximum power dissipation of 0.5 W , then the minimum resistance to be used in series with this diode for safety when it is connected to a 25 V power supply is ____\_\_\_\_ Ω\Omega.