Transformer Versus Amplifier

The function of a step up transformer is to increase the voltage that is input while the function of an amplifier is also the same.So, my question is that "Why isn't a transformer used in the place of an amplifier in many electronic circuits"??
- Prudhvi Raj Borra (age 18)
NIT Warangal,India.

A transformer by itself can change the voltage of a signal but does not change the amount of power. For a given increase in voltage, there is an equivalent decrease in the current.  The power remains constant.   In fact due to resistive losses the amount of power is actually a bit less.  An amplifier, on the other hand, can increase the power of a signal by using the input voltage to control a more powerful source.

LeeH

(published on 08/21/2011)