Question 63 of 209

The $I-V$ characteristics of a $p-n$ junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias voltage of $2V$ and $4V$ respective is

A$1:2$B$5:1$C$1:40$D$20:1$

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Answer: (B) $5:1$

Dynamic resistance of a diode is defined as, $R=\dfrac{∆V}{∆i}$.

At forward bias voltage of $2V$,
${R}_{1}=\dfrac{∆V}{∆i}=\dfrac{2.1-2}{\left(10-5\right)\times {10}^{-3}}=20\Omega$
At forward bias voltage of $4V$,
${R}_{2}=\dfrac{∆V}{∆i}=\dfrac{4.2-4}{\left(250-200\right)\times {10}^{-3}}=4\Omega$.
Therefore,
$\dfrac{{R}_{1}}{{R}_{2}}=\dfrac{20}{4}=\dfrac{5}{1}$