Power Amplifier is electronics circuit which amplify the signal. In other words amplifier is circuit or electronic device which make week signal strong. Amplifier is an essential part of mostly used devices like, mobile , Television, Audio amplifier, CD players, tape recorders etc. In other words amplifier is important part of any system, transmission system or any other. The main part of the amplifier is transistor an electronics component which amplify the signal. any signal which is amplified in micro volt or amps and output is in few amps. It is said that amplifiers can amplify signal up to 1000s of times, it is true. but keep in mind it cannot be 1 volt to 1000 volt but it can be from 1u volt to 1 volt which is million times amplified.
How Amplifier works:
The working of amplifier is as we week signal is applied on the base of the transistor it makes changes in current or voltage flowing from emitter to collector of transistor. Thus voltage measure on the resistor which is connected at collector in series, is high. it is called that signal applied on base of transistor is amplified. The value of resistor in series with collector is always high rather than resistance of emitter. These resistances actually cause amplification of signal. look at figure:
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