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PhysicsJEE Main 23 Jan 2026, Shift 1·Q12·MCQ·Easy–moderate

Semiconductor Electronics · p-n junction and diodes

The following diagram shows a Zener diode as a voltage regulator. The Zener diode is rated at VZ=5V_Z = 5V and the desired current in load is 5 mA. The unregulated voltage source can supply upto 25V. Considering the Zener diode can withstand four times of the load current, the value of resistor RSR_S (shown in circuit) should be Ω\Omega.
  1. (1)4000
  2. (2)10
  3. (3)100
  4. (4)1000

Flawed question. Dropped in the source; as printed RS=(25−5) V/(20+5) mA=800 ΩR_S = (25-5)\,\mathrm{V}/(20+5)\,\mathrm{mA} = 800\ \Omega, not among the options, and no evident intended version. It is shown for completeness and is left out of practice tests.

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