Test: Power Amplifier - Electronics and Communication Engineering (ECE) MCQ

The only use of amplifier in a circuit is to provide strength to signal. This may refer to an increase in current, voltage or power of the output w.r.t the input being applied.

Power rating is the maximum power allowable to dissipate by a transistor beyond this point transistor may behave unlikely. This is expressed in watts.

Power amplifier increases voltage as well as current. Increase in voltage or current is small compared to normal amplifiers. But power amplification has occurred ie. Voltage x current is more.

Transistor is an active device since transistor contains voltage sources which are necessary for amplification.

If the resistance of the audio amplifier is less, the output power of the transistor will be high since output current is increasing. Hence to drive a 2ohm speaker amplifier needs double power that for a 4ohm speaker.

The unwanted characteristics of amplifier output apart from desired output are collectively termed as distortion. This should be avoided.

Before the invention of power amplifier vacuum tubes are used for audio signal amplification which consumes large space and costly.

Input stage of the power amplifier is also called the front end.

In the equation of power output for the power amplifier, the power is proportional to the square of the current and inversely proportional to the resistance. If the impedance is halved then power is doubled.

The power rating is 100 W, and that is the maximum allowable power usage of a transistor, beyond which it may damage. If the power is less than 100W, the circuit operates. Near to 100W, the power may also be higher than 100W, hence that option is incorrect.