Question

Two identical P-N junction may be connected in series with a battery in three ways (fig below). The potential drops across the two P-N junction are equal in

• A. Circuits 1 and 2
• B. Circuits 2 and 3
• C. Circuits 3 and 1
• D. Circuit 1 only

Answer 1

The correct option is B Circuits 2 and 3

Let, $R_f$ is the resistance in forward biased connections and
$R_r$ is the resistance in reverse biased.

$\Rightarrow V_f=I{R}_f\text{and}{V}_r=I{R}_r$

In diagram $1$, the diode on the left is forward biased while the one on the right is reverse biased. So the potential drop across both of them will not be equal.

In diagram $2$, both the diodes are forward biased, so the potential drop across both of them will be equal.

In diagram $3$, both the diodes are reverse biased, so the potential drop across both of them will be equal.

Hence, $\left(B\right)$ is the correct answer.