Question

How do transistors amplify signals?

Answer 1

Explanation:

As we know a transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter-base junction, makes it remain in forward-biased condition. This forward bias is maintained regardless of the polarity of the signal.

The below figure shows what a transistor looks like when connected to an amplifier.

Where,

$V_i$ is the input signal or voltage.

$V_{EB}$ is the emitter-base voltage.

$V_{CB}$ is the collector-base voltage.

$I_E$ is the emitter-current.

$I_B$ is the base-current.

$I_C$ is the collector current.

$R_L$is the load resistance.

Therefore any small change in the low resistance input circuit results in an appreciable amount of change in the output circuit. The emitter current, which is a result of the input current, results in an appreciable change in the output current, which then flows through the load resistor $R_L$, resulting in a large voltage drop across it.

Hence, we can conclude that a small change in the input current results in a large change in the output current, which shows the amplifying capabilities of the transistor.