difference between an amplifier and an transformer

can anyone state the distinct differences between a transformer and an amplifier and why transformers cannot be used in places where amplifier finds its use?

Transformers are impedance changing circuits that do not add any power to a signal as amplifiers do.

what do u mean by it changes the impedance...
there are voltage n current transformers so don they also provide power to the signal and increse its amplitude

Transformers don't add power they change it. It would also be difficult to find a DC only transformer as an amplifier.

Amplfer increase teh strength of input signal.
But transormer only maintain constant level

The output & input POWER (ie, P=VxI) of a tranformer is same or equal. But, in case of a amplifier, you give some voltage say 12V for the functioning of the amplifier & it uses this voltage and then amplifier the given signal.

Well allow me to state some of the many differences existing among both amplifiers and transformers.

As their names imply, the first amplifies the signal (voltage, current, power) while the other transforms the signals characteristics i.e. voltage and current.

A transformer steps up the voltage, but then it steps down the current so the power is the same on both primary and secondary sides.

An amplifier on the contrary steps up all 3, voltage , current, and power, because it's connected to a DC supply which can help add some power to the signal.

A transformer depends on the magnetic field coupling both primary and secondary coils, and thus tranferring energy between both sides. While an amplifier doesn't operate with magnetic fields, it mainly depends on semiconductor devices that have 3 terminals, and depend upon the motion of charges in them between these 3.

as the names suggest, amplifier amplifies the signal content(ie. ac only as dc is not a signal) where as transformers transfer the signal from one voltage/current level to another conservung ac power.But in amplifies ac power is amplified.But yes dc power is consumed to supply the required amount of bias current required for the amplifier.:idea:

Amplifier (those that are direct coupled) can amplify DC signals as well. Which means SQUARE WAVE input can be amplified.

Transformer is based on inductance phenomenon which means it works on di/dt. In DC or square like wave inputs ... there is no continuous di/dt. so the transformer doesn't allow them to pass.. which means no o/p for DC input...

This is a common confusion.Can any amplifier circuit amplify dc.Answer is no.(except for clamper ckts which amplify for a short time).Because ur max. voltage will b limited by ur power supply.And square wave has both ac and dc component.
But yes u will get zero o/p if u give dc to a ransformer.