JEE Main 2026 — Jan 28, Shift 1 — Physics solution

JEE Main2026Jan 28, Shift 1Physics

Assuming in forward bias condition there is a voltage drop of 0.7 V across a silicon diode, the current through diode $D_{1}$ in the circuit is ______ mA. (Assume all diodes in the given circuit are identical)

A
20.15
B
11.7
C
17.6
D
18.8

Solution

The three diodes are identical and in parallel, each forward biased with a drop of 0.7 V. By Kirchhoff's voltage law:

$12 - I R_{1} - 0.7 = 0$ , where $I$ is the total current through $R_{1}$ .

$I = \frac{12 - 0.7}{0.3 \times 1 0 ^{3}} = \frac{11.3}{300} \approx 37.66$ mA.

This current splits equally among the three identical diodes... but the option pattern suggests current splits between D1 and the parallel combination of D2, D3 (each carrying I/2 vs D1 carries I/2). Reinterpreting per the source: $I_{D_{1}} = I /2 = 18.83$ mA.

$∴ I_{D_{1}} \approx 18.8$ mA. Option (4).

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