Question

When the voltage drop across a $p-n$ junction diode is increased from $0.65\, V$ to $0.70 \,V$, the change in the diode current is $5 \,mA$. The dynamic resistance of the diode is

• A. $5 \,\Omega$
• B. $10 \,\Omega$
• C. $20 \,\Omega$
• D. $25 \,\Omega$
• E. $100 \Omega$

Answer 1

Answer: (B)

Dynamic resistance is
$r_{d} = \frac{\Delta V}{\Delta I}$
Here, $\Delta V = 0.7 -0.65 \,V $
$= 0.05 \,V $
$ \Delta I = 5 \,mA $
$= 5\times 10^{-3} \,A $
$ \therefore r_{d} = \frac{0.05}{5\times10^{-3}}$
$ = 10 \Omega$