Modern Physics 6 Question 14
15. At $0.3 V$ and $0.7 V$, the diodes Ge and $Si$ become conductor respectively. In given figure, if ends of diode Ge overturned, the change in potential $V _0$ will be
(Main 2019, 9 Jan II)
(a) $0.2 V$
(b) $0.6 V$
(c) $0.4 V$
(d) $0.8 V$
16 The reverse breakdown voltage of a Zener diode is $5.6 V$ in the given circuit.
The current $I _z$ through the Zener is
(2019 Main 8 April I)
(a) $10 mA$
(b) $17 mA$
(c) $15 mA$
(d) $7 mA$
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Solution:
- Initially $Ge$ and $Si$ are both forward biased. So, current will effectively pass through Ge diode with a voltage drop of $0.3 V$.
$\therefore$ Initial output voltage, $V _0=12-0.3=11.7 V$
If $Ge$ is reversed biased, then only Si diode will work.
In this condition, output voltage
$$ V _0=12-0.7=11.3 V $$
$\therefore$ Change in output voltage $=11.7-11.3=0.4 V$
