Question

Two identical $P-N$ junctions may be connected in series with a battery in three ways as shown in the adjoining figure. The potential drop across the $P-N$ junctions (in each circuit) are equal in

• A. circuit 1 and circuit 2
• B. circuit 2 and circuit 3
• C. circuit 3 and circuit 1
• D. circuit 1 only

Answer 1

Answer: (B)

In circuit $1,N$ is connected with $N$, which is not a series combination of $P-N$ junction. In circuit 2 , each $P-N$ junction is forward biased, hence same current flows, giving same potential difference across each $P-N$ junction. In circuit 3, each $P_{-}N$ junction is reverse biased, same leakage current will flow, giving equal potential difference across each $P-N$ junction diode.