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Two amplifiers are connected one after the other in series (cascaded). The first amplifier has a voltage gain of 10 and the second has a voltage gain of 20. If the input signal is 0.01 volt, calculate the output ac signal.

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#### Solution

Voltage gain of the first amplifier, *V*_{1} = 10

Voltage gain of the second amplifier, *V*_{2} = 20

Input signal voltage, *V*_{i} = 0.01 V

Output AC signal voltage = *V*_{o}

The total voltage gain of a two-stage cascaded amplifier is given by the product of voltage gains of both the stages, i.e.,

*V* = *V*_{1} × *V*_{2}

= 10 × 20 = 200

We have the relation:

`V = V_0/V_1`

V_{0} = V × V_{i}

= 200 × 0.01 = 2 V

Therefore, the output AC signal of the given amplifier is 2 V.

Concept: Junction Transistor - Transistor as a Device

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