Question

Two amplifiers are connected one after another in series. The first amplifier has a voltage gain of $15$ and the second has a voltage gain of $20$. If the input signal voltage is $0.3V$, the output signal voltage is

• A. $2v$
• B. $6v$
• C. $5v$
• D. $90v$

Answer 1

The correct option is D

$90v$

Step 1: Given data

Voltage gains:

$A_1=15$

$A_2=20$

Input Voltage:

$V_i=0.3v$

Step 2: To Find

We have to find the output signal voltage.

Step 3: Calculate output signal voltage

The product of voltage gains gives the total voltage gain of a two-stage cascaded amplifier.

$A=A_1\times A_2$

Total voltage gain can be written as

$A=\frac{V_0}{V_i}$

Hence,$\frac{V_0}{V_i}=A_1\times A_2$

$$\begin{gathered} V_o=A_1\times A_2\times V_i \\ =15\times 20\times 0.3V \\ =90V \end{gathered}$$

Hence, Option (D) is correct.