Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 8

8. 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: 8. (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, $E=\frac{V}{d}=\frac{0.5}{10-6}=5 \times 10^{5} V / m$