Question

Consider the circuit shown in the figure below:


The value of base to emitter voltage $|V_{BE}|$ = 0.7 V and the value of '$\beta$' for the transistor is equal to 30, then the value of emitter, base and collector voltages respectively are

• A. 3.7 V, 3 V, 2.61 V
• B. 3.7 V, 3 V, 3 V
• C. 3.7 V, 3 V, 3.61 V
• D. 3.7 V, 3 V, 1.5 V

Answer 1

The correct option is A 3.7 V, 3 V, 2.61 V

The value of base voltage is equal to $V_B=3V$,

Thus, the value of emitter voltage,
$V_E=V_B+V_{EB}$

$=3+0.7$

$V_E=3.7V$

now, $I_E=\frac{9-3.7}{1.1}\times {10}^{-3}=4.818mA$

$I_C=\alpha I_E=\frac{\beta }{\beta +1},I_t=\frac{30}{31}\times 4.818\times {10}^{-3}=4.662mA$

Thus, $V_C=4.662\times {10}^{-3}\times 560=2.61V$