Question

In a silicon diode, the forward current changes by $2.5mA$ when the voltage changes from $0.08$ to $0.09V,$ then the forward dynamic ac resistance of the diode is:

• A. $4\Omega$
• B. $0.25\Omega$
• C. $2.5\Omega$
• D. $8.5\Omega$

Answer 1

The correct option is A $4\Omega$

Given that:
I = 2.5 mA = $2.5\times {10}^{-3}A$
$\delta V=V_2-V_1=0.09-0.08=0.01V$
Hence, dynamic resistance is
$R_d=\frac{\delta V}{I}$
$R_d=\frac{0.01}{2.5\times {10}^{-3}}$
$R_d=0.04\times {10}^3=4\Omega$