Practice portal › Semiconductor Electronics › Zener Diode as a Voltage Regulator

The value of the resistor, R_S, needed in the dc voltage regulator circuit shown here, equals [Figure: input Vᵢ, series R_S, a Zener carrying nI_L, and a load carrying I_L with output V_L.]

Asked in JEE Main Online 2015 · Zener current and series resistance

• (1) (Vᵢ-V_L)/nI_L
• (2) (Vᵢ+V_L)/nI_L
• (3) (Vᵢ-V_L)/(n+1)I_L
• (4) (Vᵢ+V_L)/(n+1)I_L

Step-by-step solution

Why the other options are wrong

• (1) Uses only the Zener current, not the total through R_S.
• (2) Adds voltages and uses only the Zener current.
• (4) Adds the voltages; R_S drops Vᵢ-V_L.

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