Question

Two junction diodes one of germanium $(Ge)$ and other of silicon (Si) are connected as shown in figure to a battery of emf $12\, V$ and a load resistance $10\, k \Omega$. The germanium diode conducts at $0.3\, V$ and silicon diode at $0.7\, V$. When a current flows in the circuit, then the potential of terminal $Y$ will be

• A. 12 V
• B. 11 V
• C. 11.3 V
• D. 11.7 V

Answer 1

Answer: (D)

Ge conducts at $0.3\, V$ and $S i$ Conducts at $0.7\, V$. Both Ge and Si are connected in parallel. When current begins to flow, then the potential difference remains at $0.3\, V$, so no current flows through Si-diode.
$\therefore $ Potential difference across resistive load $=12-0.3=11.7\, V$
$\therefore $ Potential of $Y=11.7\, V$