Figure shows a circuit in which three identical diodes are used. Each diode has forward resistance of 20 Ω and infinite backward resistance. Resistors R₁ = R₂ = R₃ = 50 Ω. Battery voltage is 6 V. The current through R₃ is: (a) 50 mA (b) 100 mA (c) 60 mA (d) 25 mA

Answer: (a). Battery's positive terminal is on the left, so D₁ is forward biased. In the middle branch D₃ faces opposite to D₂, so it is reverse biased and that branch carries no current. Total resistance in the loop: RD1 + R₁ + R₃ = 20 + 50 + 50 = 120 Ω. I = 6/120 = 0.05 A = 50 mA, and all of it flows through R₃. So the answer is (a) 50 mA.

Figure shows a circuit in which three identical diodes are used. Each… | JEE Main 2013 (22 Apr, Shift 1)

Q105JEE Main 2013 · 22 APR · SHIFT 1Medium

P-N Junction Diode

Figure shows a circuit in which three identical diodes are used. Each diode has forward resistance of 20 $\Omega$ and infinite backward resistance. Resistors $R_1 = R_2 = R_3 = 50\ \Omega$ . Battery voltage is 6 V. The current through $R_3$ is:

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Answer: (a)

Battery's positive terminal is on the left, so $D_1$ is forward biased.
In the middle branch $D_3$ faces opposite to $D_2$ , so it is reverse biased and that branch carries no current.
Total resistance in the loop: $R_{D1} + R_1 + R_3 = 20 + 50 + 50 = 120\ \Omega$ .
$I = \frac{6}{120} = 0.05$ A $= 50$ mA, and all of it flows through $R_3$ .
So the answer is (a) 50 mA.

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