Question

Consider the circuit given below:

$\text{The value of input resistance}{R}_{in}\text{is\_\_\_\_\_\_k}\Omega .$

• A. 102.38

Answer 1

The correct option is A 102.38
Base emitter loop

$500k{I}_B+0.7+1k(I_B+I_C)=12$
$I_C=100I_B$
$I_E=101I_B$
$\text{from here}{I}_B=18.80\mu A$
$r_{\pi }=\beta \times \frac{V_T}{I_C}=\frac{V_T}{I_B}=\frac{26}{18.8}\text{k}\Omega =1.383\text{k}\Omega$
$R_{in}=r_{\pi }+(1+\beta )R_E$
$=1.383k+101\times 1k=102.383\text{k}\Omega$