Semiconductor Electronics Materials Devices And Simple Circuits Ques 91
91. In the given figure, a diode $D$ is connected to an external resistance $R=100 \Omega$ and an e.m.f. of 3.5 $V$. If the barrier potential developed across the diode is $0.5 V$, the current in the circuit will be:
(a) $40 mA$
(b) $20 mA$
(c) $35 mA$
(d) $30 mA$
[2015 RS]
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Answer:
Correct Answer: 91.(d)
Solution:
(d) Current $I=\frac{V}{R}=\frac{(3.5-0.5)}{100} A$
$[\because.$ Barrier potential $.V_B=0.5 V]$
$=\frac{3}{100}=30 mA$
On an average the potential barrier in P-N junction is $v 0.5 V$ and the width of depletion region $10^{-6} m$ Barrier electric field, $E=\frac{V}{d}=\frac{0.5}{10-6}=5 \times 10^{5} V / m$
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