JEE Main · 2025 · 07 Apr 2025 · Shift 1 · Semiconductors

In the following circuit, the reading of the ammeter will be (Take Zener breakdown voltage = 4 V)

Answer: (C)

Solution

Were the Zener absent, the voltage across the

400 Ω

resistor would be

\frac{400}{100 + 400} \times 12 = 9.6

V, which exceeds the

4

V breakdown, so the Zener conducts in breakdown and clamps the parallel combination to

4

V. The ammeter, in series with the

400 Ω

resistor, then carries

I = \frac{V _{z}}{400} = \frac{4}{400} = 0.01 A = 10 mA .

The ammeter reads

10

mA.

JEE Main · 2025 · 07 Apr 2025 · Shift 1 · Single correct option