Question

A change of $200mV$ in base-emitter voltage causes a change of $100\mu A$ in the base current. The input resistance of the transistor is

• A. $2K$$\Omega$
• B. $2$ $\Omega$
• C. $2m$$\Omega$
• D. $10K$$\Omega$

Answer 1

The correct option is A $2K$$\Omega$

Given that:
$\Delta V_{be}=200mV=2\times {10}^{-3}V$
$\Delta I_b=100\mu A={10}^{-6}$
For transistors, the input resistance is
$R_i=\frac{\Delta V_{be}}{\Delta I_b}$

$R_i=\frac{2\times {10}^{-3}}{{10}^{-6}}$

$R_i=2\times {10}^3=2K\Omega$