Question

In the circuit shown in figure, when the input voltage of the base resistance is $10V,V_{be}$ is zero and $V_{ce}$ is also zero. Value of $\beta$ is

• A. $133$
• B. $154$
• C. $196$
• D. $105$

Answer 1

Answer: (A)

$133$

Given $V_i=10V,R_b=400k\Omega =400\times {10}^3\Omega$
$R_c=3k\Omega =3\times {10}^3\Omega ,V_{be}=0$
$V_{ce}=0,V_{CC}=10V$
As $V_i-V_{be}=R_b{I}_b$
$\therefore 10-0=(400\times {10}^3)I_b$
$I_b=\frac{10}{400\times {10}^3}=25\times {10}^{-6}A=25\mu A$
and $V_{CC}-V_{ce}=I_c{R}_c$
$I_c=\frac{10}{3\times {10}^3}=3.33\times {10}^{-3}=3.33mA$
$\beta =\frac{I_c}{I_b}=\frac{3.333\times {10}^{-3}}{25\times {10}^{-6}}=133$.