Doubtify – JEE Ki Taiyaari, Simple Bhasha Mein

❓ Question In the following circuit, the reading of the ammeter will be ? (Take Zener breakdown voltage = 4 V) 🖼️ Question Image ✍️ Short Solution This is a classic JEE Zener-diode regulator problem . No tricks, no confusion — bas Zener ON/OFF logic + Ohm’s law 🔥 🔹 Step 1 — Identify Zener Condition (MOST IMPORTANT 💯)** Given: Supply voltage = 12 V Zener breakdown voltage = 4 V Since: 12  V > 4  V 👉 Zener diode will be in breakdown (ON) mode . 📌 Golden rule: When Zener is ON, it clamps the voltage across it to Vz . So, V node = 4  V \boxed{V_{\text{node}} = 4\text{ V}} 🔹 Step 2 — Voltage Across Load Branch The 400 Ω resistor + ammeter branch is parallel to the Zener. Hence: V across 400 Ω = 4  V V_{\text{across 400 Ω}} = 4\text{ V} 🔹 Step 3 — Ammeter Reading (Direct Calculation 🔥)** Current through 400 Ω resistor: I = V R = 4 400 = 0.01  A = 10  mA I = \frac{V}{R} = \frac{4}{400} = 0.01\text{ ...