JEE Main · 2026 · 04 Apr 2026 · Shift 1 · Current Electricity

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Consider a circuit consisting of a capacitor (20 μF), resistor (100 Ω) and two identical diodes as shown in figure. The resistance of diode under forward biasing condition is 10 Ω. The time constant of the circuit is

α \times 1 0^{- 3}

s. The value of

α

is _____ .

(A)2.2✓ Correct
(B)2.0
(C)2.1
(D)2.4

Answer: (A)

Solution

The two diodes are connected in opposite sense, so whichever way the capacitor drives current one diode conducts with its forward resistance

10 Ω

while the other is reverse biased and blocks. The resistance in the path is

R_{eff} = 100 + 10 = 110 Ω

, giving a time constant

τ = R_{eff} C = 110 \times 20 \times 1 0^{- 6} = 2.2 \times 1 0^{- 3}

s, so

α = 2.2

JEE Main · 2026 · 04 Apr 2026 · Shift 1 · Single correct option

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